According to Cnet (which I don't really like as far as reviews go, but their
TV Buying Guide is helpful for beginners) the largest widescreen TV recommended at 7 feet is 55". No prob. BUT, for a 4:3 screen ratio the largest recommended is 36", which is what a 45" widescreen displays with the side bars. SO here's what is going to happen: You bring home this new 50" TV (doesn't matter which one) and your wife faints when she sees the price tag (hypothetically if you aren't married of course). So you set it up, but you only have standard definition programming right now because you don't get the box until you have the tv anyways. So you get it all setup, maybe even run an S-Video between the box and the tv (as opposed to the rf cable they supply you with) and BAM. This picture is worse than my old tv! How does this make sense! Why am I yelling! etc. etc. So then you will spend a couple hours tweaking the picture to basically no avail. So you hide the TV from your wife and claim that it can't be on for more than 5 minutes per day for the first week or the pixels all die and then the dead pixels attract bunnies which will eat all her flowers in her garden. Then you finally get the HD box or an antenna and everything is better, at least in those 7 channels.
The moral of the story? Slightly smaller TV, sit further away, or be prepared for a bit of disappointment at first. I personally have the 45" Sharp Aquos LC-45GD4U. I have been very impressed with it, and that is from a sitting distance of 12 feet. It's a waste of resolution I know, but it was the only distance that my furniture allowed. If you can get the 45" for under $3,000 I would recommend it, and it is future proof for awhile I would think (computer compatible, 1080p, 1 HDMI, 1 DVI, FireWire/1394 IEEE). There are 3 versions of the TV out. You might even want to consider their original model, which has a seperate jack box that connects to the TV. I imagine this would be convenient since wires are easily noticable behind this TV.
I can't believe you don't have siz listed as an issue. Of course the LCD is gonna give you the best picture, because its pixels are closer together. 1080p is irrelevant because there is no support, and I doubt you would notice a major difference between 720p and 1080p. Duration is going to be lcd again, because there are no bulbs to change every 5 years, (I think) calibration lasts longer in lcd compared to dlp, and I haven't found 1 dead pixel on my tv, and yes I did go up and stare at it from 2" away for 10 minutes until i got a headache. Your viewing distance will eliminate the screen door effect, not that it is noticeable in the first place.
In the end, only you can make the decision though. If you buy something off the internet because someone else told you it is awesome, you are setting yourself up for a huge blow when the TV arrives and it's not all you expected. Go to best buy or another TV vendor, compare compare compare, then drink alot of coffee and compare some more.
P.S. did you look into LCoS at all? JVC makes some extremely affordable ones that have an amazing picture. And if brightness is your thing, definitely give them a look. For JVC the technology is called HD-ILA, and for the more expensive Sony models it is called SXRD. There are some other stragglers in the LCoS, but JVC and Sony are the 2 big ones.
Good Luck and Happy Hunting
