What OS does she intend to use? OS X i'd guess?
I'd take a look at this site for starters..
www.osxaudio.com/
If she wants digital audio.. There are plenty of USB audio interfaces.. And USB is fine for stereo use. But personally I dont trust it for multichannel work. So if stereo is all she needs, then there should be no problem with USB audio interfaces (I used a roland one for a while with no problems). And many of them have digital inputs and outputs, as well as analog.
As for Midi.. There are stacks of USB midi interfaces available that work on macs. I always found them a complete pain in the ass to set up in OS 9. But in OS X, it should be pretty straight forward. Also, for ease of set up, i'd always recommend buying a midi interface which is the same brand as the sequencing software you are using. It isnt essential to do this, but it really can help a lot.
All the best..