Until recently no. I just playted on a shitty little old 19" normal tele quite happily.
I got a new samsung 32" HDTV now (play: £329!) and to be honest my crappy old eyes have only noticed a bit of sharpness and the fact i have to turn my head this way and that while playing street fighter 4 as the characters are so bloody big. (but that's down to the size of the tele.)
Yes it's pretty, but next gen graphics are pretty anyway. I don't think a new tv is going to help me beat niknak on halo 3 :P