Subwoofer in ceiling

I wish to avoid having the big black sub woofer box sitting in my lounge room and I am considering either mounting it in the ceiling or under the floor. I don’t care for heavily subwoofered music but appreciate the effects when viewing a surround sound movie.
The present plan is to remove the component with on/off switch and other controls and mount them within the same cabinet as the amplifier then run speaker wire to an enclosure in the ceiling with speaker directed down towards the room.

Some queries I have are: Will it sound weird having the sound come from above? Should I mount it above the veiwing screen / does it make any difference where these low frequencies come from? Would the effect be better if it was mounted under the floor? The ceiling material is thin fibre cement board .25 inch. Do I need to cut vent holes –I suspect that with 200watts the sound will have no trouble passing through but will this effect it’s fidelity?

If anyone can share their thoughts on this it would be appreciated.

Les, IMO mounting a sub in the ceiling is not going to give you the sound effects you are seeking. Installing a Butt-Kicker under you seating position may be the route to go. However not if you have plaster walls. There are listening chairs,& sofa's available now that will shake the &*$# out of you during a dinasours approch, if you have an unlimited bugdet? 200 wpc should be affective, as long as the subwoofers .1 LFE will hit a low-end of under 25hrz. 20 hrz would be more appropriate for H/T. Pick up a copy of Widescreen Review at the newstand, they offer a special Subwoofer Review Guide also. Good luck!
Check this out -

Floor may be a better locale - you may eventually crack your ceiling plaster, and if you have recessed lights, their housings may buzz along with the sub.

Also look at the Sunfire True Sub Jr. - it's small and mighty, and far simpler than the in wall route.
I agree with everyone else, the ceiling is probably not a good place for a sub. It may sound ok until all of your lights rattle loose and the plaster cracks from vibrations.

They do make subs for under floor installation. All you need for this is a small vent in the floor (ie an air conditioner register) for the sub to work. These subs are designed to fit between standard 16" floor joists quite nicely. I saw them not long ago at either mcmelectronics or parts express. You could always use a niles, snell or sunfire in wall sub under the floor also. JUST REMEBER: once it is installed, you can't move it. It may be worth having a pro do this with proper equalization?
I found this link in my bookmarks which may be useful to you: Hope it helps.
Boston Acoustic also last year came up with a subwoofer that fits in the floor joists you could check out?