Yup, got both latest available drivers, chipset/x-fi drivers. My mic is unplugged, and I still get the horrible squeal. I did have the mic unmuted though. I'll try muting pretty much everything I don't need, just to eliminate any other problems.
How I fix it though, is launch the Audio Console, and switch to another mode for a second, then switch back. Once I do that, I hear a click, which I think is the card actually resetting itself. I actually use the different modes, but the mode that gives me grief is the Game mode. Audio Creation mode works good though, but I have my audio levels zeroed out in that one, where I use a tweaked set of levels in the Game mode. That's why I wouldn't use Audio Creation mode for everything.
The X-Fi never gave me any grief in my old VIA-based board, but I recently upgraded to an Intel P35 chipset based motherboard. (Asus P5K base model, yes the Onboard audio is disabled in the BIOS too.) Seems that this card doesn't play very nice with the microphone on this system anyway. I tried a voice audition, and I had some horrible background buzz. I'll try that though, and keep my fingers crossed. Thanks for the help!