PS3 Graphics power = ?

I understand additional features like extra players, better online play and whatnot... but lets be honest here, your TV can only handle a pretty low-res picture anyway. I just don't understand why the PS3 and xbox360 seem to keep boasting that they have more graphics power than anything else. I mean, a standard tv only has 480 lines of horizontal resolution.. the best tvs today only 1080 (interlaced). I'm a n00b to console gaming, so I feel like I have to ask.