Ok, if I had seen this thread early on and realized that you had a Gateway FX6800 series system, I could have saved you a lot of trouble.
The Creative X-Fi MB is an OEM solution for which neither Creative nor Gateway supplies updates to. This solution which came with Vista, was only meant for Vista x32 & x64 systems.
X-Fi MB is not compatible with Windows 7 and as you have found out from this thread, it will not be able to find any qualifying devices on the system.
To top it off, the other X-Fi solutions which have come out for Windows 7 are meant for the various PCI Expresss cards which are out there.
One thing that Gateway (Acer) has recently done though is they have released a Cobbed Windows 7 X-Fi MB version which I have found on their FTP site after 12/23/2009.
You can find it here under the FX6830 listing which if I recall correctly is the Core i5 system.
Gateway FTP for FX6830 Creative_Audio_XFI_MB.zip 30656 KB
I find there is no reason to install this on my system as it's running really good and I don't trust Gateway (Acer) solutions.
For those of you with Gateway FX6800 systems who have not seen these threads yet, here are a couple of links you might be interested in.
Thread started 12-24-2009
FX6800 New BIOS Out 842P181G
Thread started 03-18-2009
Gateway FX 6800-01e BIOS Update from Gateway Unsupported
One thing I'd be interested in knowing is if the FX6801-01, FX6801-03, and the FX6802-03 use a different motherboard from the FX6800-01e and the FX6800-05.