If you have a new HDTV, chances are it has a DVI input. I'd recommend you go with a DVD player that has DVI as an output.
There are very many very good DVD players with progresive scanning and some cheaper ones that just don't cut it. First, be aware that some companies onlly make progressive scanners quality is variable. There are progressive scanners to be aware of and perhaps others hereabouts might expand a bit on it.
Another consideration has to do with the ability to perhaps play DVD-A music. I happen to own three DVD players and only the Marantz has a decent progressive scanner and it will also play DVD-As. Not that I own a lot of DVD-As, but when I like my options. You might even get a DVD-A and bring it to the show room to see if it will work.
There a several things you should consider. First, what type/model of HDTV do you own? Second, do you currently own a (non-progressive) DVD player? If so, have you tried it with your new HDTV? I, for one, am getting tired of the marketing hype where they always mention "progressive scan DVD player" and "HDTV" in the same breath as if the new HDTV "REQUIRES" it. You may not necessarily benefit from progressive scan depending on your other components. If your new digital TV has a high-quality line-doubler built in, you may be surprised how good the picture from a "standard" DVD player can look, especially when using a component video connection. Chances are you were not taking full advantage of the performance potential of your current(non-progressive) DVD player if it was connected to a standard (NTSC) television.
All DVD players must perform some sort of "in player" letterboxing to downconvert anamorphic DVD's when connected to an analog (non-HD) 4:3 TV set. Many models get poor marks for how well they perform this funtion and the results can be an overly "soft" image or other artifacts in the resulting video. However, these same players can look much better when connected to a 16:9 HDTV. You will then bypass the player's "in-player" letterboxing circuit (by selecting "16x9" in the players's setup menu) and it will properly display the full resolution available in anamorphic "enhanced for widescreen" DVD's on your new set. It will, in effect, "open-up" the player's full video potential.
UncleJeff is right when saying beware of some budget-priced progressive scan players. The de-interlacing they perform may be much worse and produce more artifacts than a quality line-doubler built into many of the late-model HDTV's available today. It really depends on your specific equipment/system. If you run a cheap DVD player in progressive mode, it will bypass the monitor's line doubler. If the set's built in line doubler is of higher quality, then you should feed it an interlaced signal to take advantage of it. Test it both ways to test which picture you prefer. The DVI output provided on some recent DVD players can be excellent, but the benefit is seen most on fixed-pixel displays (such as plasma, for example).
By the way, you might want to save your DVI input on your set for connecting your HDTV tuner box to take full advantage of the HDTV signals' higher bandwidth. (Most of the current crop of HDTV's provide only one DVI input except a very few models that provide two DVI inputs at this time.) or unless your TV has the digital tuner built-in.
My $.02 ;~)
I think the last post was a bit winded. If your display upconverts 480p to 720--- Then yes a progressive player will kill any 480i player. Generally, the scaler in the better dvd players will be better than that of the display within the tv. How large an image you are seeing IS important. On a smaller set it is less important.
Winded? Do you mean "long" or "full of hot air"?
Hopefully the former and not the latter. ;>) JZ
P.S. I'm not against progressive scan DVD, I was just trying to cover some general points of "what to watch for" from Aniesen's original question and progressive-scan quality can vary a lot among different players. I think 480i should at least be considered if it's right for his system. I got the impression from his post that he was looking for some basic general guidelines. We can get more specific if he provides more information on his particular system.
P.P.S. I'll add that one important thing to watch out for with a progressive-scan DVD player is to make sure it has aspect-ratio control if the display device does not (when fed a progressive video signal). Many HDTV-ready 16x9 tv's will default to the "FULL" mode when fed a progressive signal and therefore will not display non-anamorphic DVD's properly. Refer to your set's owner's manual for details on how your set handles this. Many rock concert DVD's, for example, are presented in non-anamorphic letterbox format and will not be displayed correctly if the TV is stuck in the "full" picture mode. To work around this, make sure you can control the aspect ratio in the (source) DVD player. You can go out and buy the "best" brand/model of a component but if it doesn't work well together in YOUR system you will be frustrated in the long run.