What Is The Difference Between A Blue Ray And An Upconvert HDTV's, Please Help (2nd Posting) Really Want To Go Shopping.?

HDTV's, please help (2nd posting) really want to go shopping.? - what is the difference between a blue ray and an upconvert

Ok, so I finally got the difference between 1080i and 1080p HDTV, now what?
You probably could not afford a 1080i or P (the desired size of approximately 42 cm ..), so I looked into the 720's. The only people who find only at 720p. Do not a 720i? Next question have 1080i and 1080p Upscaling DVD palyer, if I is a p 720p DVD, or I should I get or make it really make a difference (which is the same price.)? It would be much the same appearance, or p, as shown in the same format, or is the best because everything I with pixels? Should I even have a DVD player or upconvet you need, if your TV is HD? I have a PS3 that plays blue rays is that the best picture? I'm sure there are other issues thatto do and I'm so if you have more information, please let me have to know what I know. Thank you.