There is no i5 700 :-) The 750 is an excellent gaming CPU - nothing noticeably faster exists. A current gen i5 would be an improvement only in non-gaming stuff, and not a huge difference even there. Just to clarify, the Celeron isn't actually part of the equation?
Sorry, I was about to double post because it wouldn't let me edit, but yes, the Celeron is the processor of the laptop I'm using to post this now, so it won't be used with the PC I'm looking to buy, no.
Also, can you guys check out the novatech link I sent - it's a different card to the 7750 I sent, and is it any good? 4GB is pretty nifty and the reviews are very good, my friend uses/recommends it also.