The P5Q-E is more expansive than P5Q, but what is the difference? I am looking at the specs and I can't really see any. Only difference I see is visually the mobo looks different. A bit bigger, I think?

Go to the asus site, check the specs and components and the mobo cooling used.

I went to the Asus website like you suggested, and it seems like the P5Q-E is bigger and has two PCI-E slots with crossfire enabled, which the P5Q doesn't.

the p5q-e its the next best option if you're not getting a deluxe. As far as the P5Q vanilla model if that were an option why not just get the pro? but then for just $10 you can get the -E

Actually at my store it is more than just $10. And why do I need two PCIE slots and crossfire and all if I am not going to use it?

Only you could answer that question.

Its for just incase you plan to crossfire. The bios settings for the P5Q-E has more overclocking options than the P5Q.

* Additional S/PDIF optical - better in most cases