8800GT overclocking, bottleneck

whats goin on, dudes?

so i got that MSI 8800GT with the sweet cooler from the Egg for $200.
i love it.
it idle's around 47.

so, naturally, i'm thinking about overclocking (crysis is the only game that i can't run at max)
but i hear MSI voids the warranty for overclocking.

so he's my problem:
i'm running a Pentium D @3.0GHz (waiting for nehalem to upgrade)
with 2GB of 533Mhz ram.
vista ultimate, 32bit

if the my GPU is bottlenecked, i dont see the sense in overclocking and voiding the warranty.
but if i will see a performance boost, i'll go for it.

thoughts?

thanks.