Thinking about making a purchase on one. Specs indicate it would hold its own pretty good. Especially with a gig or two of RAM.
I am using a friend’s Mac Mini to record an album. He is on OS X 10.3.9, 1 GB RAM, and an 80GB Hard drive. We are only doing 4 songs there, so I’m not to worried about space (otherwise, I would definitely recommend something larger). For input, I have a Phonic Helix Board Firewire 18 mixer.
As far as CPU usage goes, it handles things quite well. We have 7 tracks for the various drum mics, 4 Guitar tracks (2 left, 2 right), Bass, Synth, and 3 Vocal tracks. I can run the usual plugins (not heavy) like compression, EQ, reverb, etc. without too much CPU load. If things do get bogged down, you can always freeze tracks.
The one limitation on the default hardware has been the hard drive. We can track right around 8 simultaneous 24-bit 44.1kHz tracks before it starts dropping out. If you need to do more tracks, get a faster hard drive. If not, don’t worry about it, you should be fine.