Go over to Best Buy and have a look at an HDTV on display. Anyone who says it doesn't make a difference is blind.
AND... find out if it's a true Hi Def picture you are looking at. A lot of times places like best buy and circuit city just play dvd's on the hd televisions. That's going to look good, but it's still just 480p. 1080i/p will knock your socks off. :)