Room: 16 x 18.5 how big of tv?

HI folks...thinking 42" plasma for this i need to go bigger or will this suffice? thanks...
Go as big as you can afford to.
You really need to tell how far you are going to sit from TV rather than how big your room is, I can say I am in a 14x24 with speakers out almost 4ft from wall so I have 20ft left over, I sit 11 feet away and I run a 90 in screen with a Projector. If you have no issues with light control I suggest you look there, my 720P HD Panasonic unit and budget screen was only $800 and thats cheaper than most budget units of 42 and certainly above.
If you google HD screen size and seating distance it will give you an idea of ideal size to look for, with HD units and signals you go as big as you can within reason, not like the old days where you had to sit so far back for proper picture to avoid seeing pixels.
They had an Aquos rep on Fox and Friends this morning and I believe he said the tv height should be no less than 3x the viewing distance. But then, he sells tv's.
Get a 50". Almost no one ever says they bought one that was too big but a lot of people regret not buying a bigger one. I got a 50" 720 Panasonic for the living room and my wife picked out a 42" 1080 Panasonic for the bedroom. The 50 was $1200 and the 42 $900 at costco, which I recommend. Unless you watch mostly Blue Ray I don't think you will see a difference between 720 and 1080.
I have a 46" and sit 10 feet away. I wish I had a 52".
If you are sitting 10' away or farther from the TV you would probably want at least a 52". If you Google it, there are charts which give good recommendations.
I'm with Cnad here. Bigger is better.

The caveat I was told about large displays/screens is to prevent 'having to scan with your eyes' from side to side the images on the screen. Although this is unavoidable in theaters at times, but a consideration for one's home setting.

I sit about 8-10 ft from a 59 x 99 or so inch, screen so i CAN SEE IT AS WELL AS POSSIBLE. I got roughly $900 or so in the DLP PJ and DIY screen and I'm pretty happy with it as it suits my own more 'special' needs best. I think that's the ticket always too. Suiting your own prefs and needsn in the areas of video and audio rather than the projected or presumed needs of others by compromising those of your own.

Eye strain, and eye fatigue are worthwhile considerations. So the bit about not having to scan repeatedly, the screens images to gather it in fully however does seem a noteworthy item, given you have good enough vision to begin with I'd keep that in mind.... yet still, big and bigger to a point is sure better. I get a bunch of Wows! from others when they view mine, including my own "yep, that'll work!".

...and yes I can control the lighting entirely, though my own situation allows for some light without degrading the color or image significantly by all accounts.

Good luck.
Bigger is not necessarily better -- it all depends on viewing distance -- you don't want to be so close that you see the pixels. You can find general rules of thumb based on viewing distance by searching the web.

I've read that 50" is the minimum size for making one feel "in" the image, but again it depends on viewing distance.
Take your viewing distance and divide it by two, that should be your screen size.
10-11 ft will never be too big for 90 inches and below with any HD signal, DLP Projectors can give some showing of pixels as you get cclose but even then the distance of 10 or so feet is a non issue.
Get as big as you can and you might be shocked to find how cheap Projectors are if you can control light and dont need to cycle it on and off many times per day................there is nothing like a great flic or even a concert DVD on a nice big screen.sports too!
It isn't perfect or followed by any particular guidelines but here it goes:
I have two displays in my listening room.
* 50" 720p Pioneer plasma
* and 1080p Optoma DLP projector and 84" motorized/tensioned screen

Viewing distance is 12' to plasma display and 11' to motorized projection screen.

Pioneer is great on SD as well as HDTV and looks better then my newer 47" LCD 1080p display but nothing in comparison to "big screen experience".
Depends on your seating distance. I wouldn't go below 100" diagonal for an 11' viewing distance or 110" for 12'.

Seating at 1.5 x screen width for a 16:9 screen is an OK compromise which doesn't make lower quality sources too big or good scope DVDs too small
A Big Screen experience really requires a big screen. it's really the icing on the cake. the word Theater kind of says it all, doesn't it?

I've not been to a theater that used minimum sized screens. I had a 61 inch in my 14x20 room before this larger combo of 720p DLP PJ & DIY screen. there is no comparison. I've asked people who have pretty good eyes to be as critical as possible and tell me where and/or how it is less than great or if there are any distracting artifacts being displayed... no one has seen any screen door effet, pixels, rainbows, etc. The only knnock, if you will, is this display does not have the sheer intensity of a regular CRT TV. Several have said this image is better overall than their large 36 - 46 LCD screens as there isn't any ghosting of rapidly moving images as is more common on LCD TVs.

All of these notes have been given without me telling them I've got the PJ set to it's low output setting to extend bulb life either.

Bulbs cost a lot. $400 each. Very true. I don't know how long or how much life I'm going to get out of mine in fact on it's lower output setting, but it is projected to be around 4-5000 hours by the BenQ team. But say it is only 3000.

3000 hours equates to more than 8 hours a day for one full year... at a cost of 13 cents per hour.

If it’s not used as a primary TV source a bulb purchase comes even further down the road for you. I use mine on avg thus far about 8-10 hrs per week. On paper I should buy a bulb in just under four years.

So for at or under $1,000.00 entry fee, I’m quite pleased of course… so were those who’ve watched it.
Jim I did mine for $800 (720P Panasonic LCD) and a 90 inch $100 manaul pull down......for what it is and its use its pretty awesome. I still am surprised how few take advantage of Projectors.
I know.

Mine wasn't much more. Should have been less but I paid some yahoo to install the PJ as I didn't trust myself in that capacity... yet I should have as the job was lousy and needed to be redone to align right. the guy charged me $200+.

$550 for the BenQ PE 7700... $200 for the screen materials including the black velvet trim tape, for a 116 diag. picture... $65 for a 26ft. HDMI cable... $135 for the Wirehider conduit for it and the speaker wires.

Mine is wall mounted and resides behind curtains that I’m getting put up this weekend I believe.

Spending $3000 +, a few years ago for a 61 inch Sony RPJ cured me from spending lots on small displays. It’s also cleaner looking, interferes less with the 2 ch audio system, and virtually disappears when not in use.

In fact the idea was to have something which did not affect the 2 ch audio nearly as much as a large glass lens, or big ol’ box sitting there behind the speakers allowing the sound to gather into pockets above and beside it.

… and let’s face it, when it comes to detail and video resolution such as plasma’s provide, even if I wanted to see the hairs and pores on peoples skin, or each blade of grass… I can’t. If I could I would have a plasma in my BR or office… and still have the PJ + big screen outfit in the main HT room.

That the single most significant item which provides the greatest impact in an HT system is a theater-sized display… IMO
Yea I did mine to get best 2 channel with nothing in the way, it just was a huge bonus that the cheapest way was actually the biggest picture.
Before we got the TVs I mentioned I had a 36" Sony hi def CRT and my wife had last years Sony 32" LCD. My picture was , to my eyes , considerably better than the LCD. But I haven't missed it for a minute since I got the Panasonic. I sit about 8' (at most) away and the picture is as good as the source will allow. Has anyone noticed how much better the picture and sound is on the new show "The Mentalist"? I watch it as much for them as the story.
Go down to Best Buy or Fry's electronics and buy yourself about $1,000 worth of projector. Take it home, hook it up and throw a hi-def picture against one of your bare walls. You'll be surprised at how good the picture is. If you are not blown away, take the projector back for a full questions asked.
Good point... stop by a dept store and get a king sized sheet and duct tape too. You can take the sheet back as well when you build or order your screen.