You can get an 1156 that will meet his requirements for around $130, even a crappy Asrock X58 is still $200. i5 750 will play all the latest games at $248 while the lowest i7 (still better than the i5) is $350+ i7 jacks up the cost pretty quick and then eats into the money available for a GPU which you'd want to be able to do 1920x1080 with vsync.
The i5 OCs fairly well too.
I like spending other people's money too but 'gaming pc' is a very loose term, just look at dezz' FS thread, lolerskates.