I have a pentium 4 CPU @ 2.54 GHz
1 GB ram ddr1
250 gb HDD
How to improve hardware (without changing video card!!!) to optimize gameplay?

Hey, im building a new computer which is:

Q6600 2.6Ghz x4 (might overclock it if it will make a big difference)
4GB 800Mhz RAM
nvidia 680I chipset mobo
8800GT GPU

Will one 8800GT be good enough to run new games (such as bioshock, UT3 etc) on high/max settings at resolutions of 1680x1050, as i have just got a new monitor and want to take advantage of it. Bear in mind that i dont expect to run crysis on max settings, as this is an exception.

My budget cant stretch much further, so i am not considering a huge improvement in the hardware listed above.

How do you think the system will fare against new games, and would id be able to perform well if i reduced the resolution?

Thanks for any help