Depends how he plans to go about it to be honest, if he's doing multi-track work and planning on tweaking each track up to production/demo level, then I'd suggest something a little more upmarket, else something like an Audigy will be perfectly acceptable, that's got 48Khz, 24Bit recording which should be enough to minimise distortion.
Audacity isn't the best program in the world, but the problem is that the really good ones aren't cheap. Once again though, it depends on exactly how your friend plans to record on it.
Edit: And for 'upmarket', I mean something like the Audiophile or the E-MU range, they aren't pocket busters, but they are more expensive than a standard sound-card.