i've installed the latest soundblaster driver for the soundblaster audigy but i'm not sure anymore that this driver includes asio driver. but i also could not find an extra asio driver for the card although i know it is "asio - able".
I have had some experience with SBLive! and the kX ASIO drivers. They seem to work ok. The kX drivers also work with the Audigy and will give you a total of 16 ins and 16 outs which are routable in a DSP patch window (... the card does not have 16/16 analog IOs ;-))
See www.kxproject.com for more info.
/Soeren