FWIW, I have the SB Audigy right now, alongside the onboard Realtek ALC889A without too many problems. Creative drivers on the other hand... ugh. I couldn't get them to install correctly because apparently Creative removed them from their site, and Windows Update doesn't give the proper one, so I kept getting BSODs. Luckily, I had the CD in addition to the original Driver download files from my previous PC build so I installed those sequentially and finally got it updated. Driver headaches aside, I did run RMAA (RightMark Audio Analyzer) on both of them and they're about even. Onboard actually wins a little due to it not having the ridiculous intermod problem on the Audigy but it has quite a bit of low frequency noise that the Audigy doesn't have.
I've been thinking about posting the results but I can't imagine too many people would find it useful since the Audigy 1 is so old.