There will be no bottleneck especially if you overclock that E8400 to 3.4/3.6 or better as they are great overclockers.
I upgraded from an EVGA 9800GTX+ to an EVGA GTX460 and my FPS basically doubled.
Your PSU is fine.
awsome guys good tips,
is it true ati's new ards are coming out dec/jan? so then gefore cards will drop in price?
Close Ati already released the 6xxx series and the GTX460 has already dropped in price. The 1GB models that were $240 at initial release are closer to $200 now and you can find them even cheaper with rebates if you shop around.