have you tried using the XP dirver? my audigy2 ZS also performed sucky when using the Vista Beta driver, but i installed the XP driver, and it performed, well, as in XP

if the installer won't run or something similar, try manually installing the driver from the Device Manager.
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AMD Athlon II X2 440 @ 2.7 GHz (Sempron unlocked)
2x2GB OCZ DDR3 1600MHz 8-8-8-24 AMD Black Edition
Gigabyte GA-890GPA-UD3H 890GX
MSI nVidia GTX460 1GB Hawk
X-Fi Titanium Fatal1ty Professional
Antec TruePower New 650W