I think you have to purchase an HDTV now. you have a blu-ray player in your PS3 and that's the only reason I purchased a PS3. It's worth it just do some research on different brands, then find one that gives you a picture you like. good luck!
Yes I agree that you should get one, it is said the price for tv has dropped a lot the Westinghouse LVM-37W3SE 37" 16:9 8ms 1080p HD is on sale for $800 now. And the Philips USA 42PFL7422D 42" widescreen 1080p LCD HDTV is only $1240. And the Philips 47PFL7432D got pretty nice reviews.