I have just built a new PC and everything seems to work fine apart from the sound card. It's a Creative X-Fi XtremeGamer Fatal1ty Professional Series and I'm sure that its physically installed correctly in the PCI slot on my motherboard. However, when I first started Windows Vista Ultimate 64-bit, it didn't give me a balloon or popup or anything saying "new hardware detected" and when I tried to install the Creative drivers which came on a CD, they said they couldn't find any applicable hardware. Is it something to do with the BIOS? or could it be a faulty sound card? I've already e-mailed the retailer, just thought you guys might be able to help more immediately.

Specs:
Asus P5K
Intel Q9450
EVGA GeForce 9800 GX2
4GB Corsair Dominator 1066MHz RAM

Thanks guys.

Have you tried their latest beta driver here?

I tried the latest drivers but that didn't help, I then contacted Creative and they told me to try a different slot (something I realy ought to have thought of myself). That worked so now I'm worried that my mobo has a dodgy slot .

Most of the drivers and apps on the cd are obsolete. Have you made sure you have turned off onboard sound if you have it?

Look in the manual. Your PCI slot is not dodgy.
Most PCI slots are also connected to other "onboard" solutions. (eSATAchip, onboard sound, LAN, etc.)
(table with PCI slots vs. INT#A , INT#B, etc.)
X-Fi needs a PCI slot that has busmaster capabilities. (something todo with direct memory access (DMA))
If you happen to use a slot with a "onboard" solution also is a busmaster, either your "onboard" solution won't work or your PCI card.