720P to 1080P???

You cannot. You can change some settings in display so you will use PS Smoother or Upscaler(for DVD), but the game will not run in 1080p. You can check your game's box on the back for supported resolutions: if it says 1080p, then you can run it Full HD, if not, it will run 720p. That's why it's best to get a TV with a native resolution of 720p, as you'll be able to play all games without the delay it takes the PS3 system to change from 1080p that is your XMB resolution to that of the game, and the game that will not run 1080p will look better on a display with a native resolution of 720p, than on a Full HD display.