For TV? Oh yeah.. With that Microsoft payout they agreed on (when they reneged on the buyout of Ironworks) I bought a 51 inch projection HDTV in 2002 (Hitachi, which in projection, they rule) 1080p didn't exist then, and I don't mind really.. but yeah, you will want at least a 41+ inch TV if you're mainly going to use it for watching DVDs/TV, but remember, using it for a computer, its not a good idea--text is way hard to see even in HD via PC.. (at least for PS3's it is, you gotta zoom in to see small text).
Base the size on how far you will be from the monitor/TV.. If you have a smaller room, 51 inches or less is good, anything else will be overkill.. I COULD have bought a 62 inch TV back then, but they said it would look odd, and you can even get vertigo
dunno about THAT, but yeah, we have a good size, and I even took the back off, dusted the 3 huge motherboards in there, and the 3 lenses as well. But projection TV's are being phased out now. (selling wise).
If anyone can answer this question--with projection TV's, you have to align the Red and blue grid any time you move it, as the magnetic alignment will shift the lenses guidance. Do LCD or Plasma need this alignment as well? (Our TV is 6 years old now, and I keep it aligned perfectly, and the colors/blacks, whites and picture quality are freaking amazing in HD!). And FINALLY, channels are getting their act together and adding their HD channels. I'm STILL waiting for Brighthouse cable to add HD Sci-Fi channel. (to see Stargate Atlantis and BSG in HD).
I *LOVE* the Science Channel HD!