Do you use midi at all? If you do, then go for the Audigy Value, the cheapest Audigy possible. It ain't really a very good audio card but sufficient to start with. But it does handle soundfonts directly really well. The older soundblasters are/were notorious for noise, lack of preamps and are only half duplex (cannot record and playback at the same time, hence lots of white noise).
But if audio is more your thing, then the Delta 2496 is a great starting point, as acidrock posted. He was also absolutely right to suggest HS2002 instead of Sonar 2.0 and use the difference in cash to fund the better soundcard.
I have a dual card setup, a soundblaster Live! for midi work and a Delta 66 +omni I/O box and it all works fine. I started off with a s/blaster 64 gold, migrated to the Live! and then added the delta & omni later on.
If I had my time again, I would have gone straight for the delta 2496 and used a software program like ProSynth Live for my soundfonts. The noise from the s/blaster drove me nuts.
Hope this helps.