I may be the only one who suggests Vista.
when i first got my mbp, i installed xp and after the first reboot it crashed and never got it running again...
after a few hours, i decided to install vista and so far it's been working great! sure i'm not saying vista rules, coz it surely doesn't... but, it perfectly fits my needs and looks a little bit better than xp...
ohhh and finally, i know most people will tell me: i've got xp working great... i know, my friends too... i just don't know why it happened to me, but really, i could only use it ONCE. after that, it completely broke.