Help! I ordered a nvidia 9800 GX2 and am using it on my Abit AA8XE. My PCI-E Bus speed is listed at 33.33mhz in the Uguru bios. I feel certain that by overclocking this bus speed I will enhance my Crysis pleasure. How far can I or should I push this speed?

Wasn't that PCI at 33mhz and PCIE at 100mhz? either you're making a mistake or your PCIE is very underclocked.

It's a poor idea to OC the PCI slot, which is rated at 33.33MHz. The PCI-e slot is probably the one you're talking about, after all that's where the 9800GX2 goes in. The normal speed is 100MHz, but you can safely increase it to around 115MHz, at least according to several people.
 
Performance gains are usually real small, it's pretty much pointless to increase it. Nonetheless, some people gained respectable performance and OC.

So if you set the Pci-express to "Auto" in the bios option, it will automaticaly runs at 100mhz right? (assume everything is on "stock" options and speed)