I have a 20' Flat Screen TV that's about 9 years old, it has the RGB outlets in the back and it's not HD, it uses 480i i think. It's ok but its real big and takes a lot of room and I am deciding to upgrade. I am thinking between the sizes of 26'-32'. I don't reallllly need 1080p, but it would be nice. I will be using my TV for mostly gaming with my PS3, watching movies, TV (football season) and more. Again this is for my room not a big family room. My budget is around 400ish. Now I don't exactly need 1080p, but then again like I said it would be nice to have the best right now. Is 720p 1080i still really good? Would I notice the difference between 1080p and 720p like a lot? Thanks guys!
Depending on how close you are (I assume you'll be on your bed.) with anything under 30" you won't notice a difference between 720p, 1080i, or 1080p. With a TV that size more than 6' away your eyes just can't pick up the difference.
I'd recommend getting a 720p/1080i with the highest contrast ratio and lowest response time you can afford and make sure to look at it before you buy. Watch it until you know how you feel about how colors are displayed. Brightness is slightly less important since bedrooms are usually heavily lit.
TVs in the size and class range you're looking at vary widely in quality. Pic the one you like best that has the features you need.