I'd definitely agree that a mic preamp is the next thing to save for. I think it'll give you the biggest improvement in quality.
However, I think you'd notice some difference between an Audigy2 and say an M-Audio card for 2 reasons (IMO):
1) M-Audio uses tried & true quality A/D converters.
2) The amount of bells & whisles Creative crams into their products to appeal to the general (non-recording) public. While I haven't used the Audigy 2, I'd bet there are a ton of features you don't want and won't use, cluttering the hardware, software, and signal path.
...producers
That being said, it IS a 24/96 card, and the Audigy line is said to be a few steps above their other products, and I bet it wasn't cheap. If it were me, I'd stick with it - you'll probably do just fine. However, down the road if you decide to upgrade your card, stay away from Soundblasters. Casio makes some very nice keyboards, but they're still Casios, know what I mean?