I hear Audigy's are great. I think the cheapest one will work fine if you don't need the digital SPDIF output. The next one up (ZX ?) has this output and is < $90.
DJ229 - AIR MAFIA
Water Cooled Barton 2500+ @ 3200+
Asus A7N8X-E DLX / Antec 480 PSU
1 GIG Mushkin PC3500 Level 2
ATI 9800XT / CAT 4.8
XP Pro SP2 / Soundstorm Audio
CH USB HOTAS / TrackIR 2
50" Panasonic LCD RPTV