both are tempting, but maybe the 6300+gtx would be the better option, just make sure you get a good mobo to oc the cpu. you can always upgrade ur cpu but a massive card is gold. but keep in mind that the intel cpus are going to have price cuts in april so if you can afford to wait you can get a E6600 for $224+tax(+shipping) and i'm sure the 8800gtx price is going to go down a bit
I'm pretty sure the 8800gtx will fall in price when the r600 ati cards are released.
Get the E6600 as it has 4mb L2 cache compared to 2mb cache that the E6300 has.
It is easy to say "wait a week because hardware x is coming out" or "wait a month because hardware y is coming out". The reality is that you could find yourself waiting forever if you always waited for the best thing to be released.
In this case, if you might consider settling on the 8800gtx and the E6600 (the set-up i so happen to probably be getting aswell) and if the price of this is too high, wait untill the ati r600 is launched. Then the price of the E6600 and 8800GTX will most likely have fallen noticeably.