For me, gameplay is more important than graphics. Although I'm an owner of all 3 (ps3, 360, high end computer) I do buy the exclusive only titles for the ps3, most recently uncharted 2 which has beautiful graphics as well as solid gameplay. But when it comes to multi-platform releases I choose 360, mainly due to the online experience.
Lighting and texture is always better on a high end current PC, but with ps3 vs 360 I'm certainly not going to nitpick it. It's still fun to play, regardless of the minute differences in graphics between consoles.
If you're more about graphics than the overall experience, then just build a current gen PC. If you want a great gaming experience, get a 360.
/end rant