Thanks for the responses so far folks. I have a Dell laptop (running XP) but use it for work, the intent of this proposed set up would be to use it as a dedicated audio front end. Put the 'puter, external hard drives, and small screen on my audio rack and leave it set up. So an Airport Express, additional RAM etc. wouldn't be necessary.
I haven't tried this idea with my current laptop since it wouldn't be pressed into service as a jukebox for any length of time. The digital jukebox would be used with my main system: please click on My System and take a look at the associated gear if you're so inclined.
Since I already have the hard drives, USB hub, and decent interconnects I'm thinking I'd spend an additional $1000 for this jukebox rig. The Mac Mini is half of the budget, so I'd allocate $500 for the DAC (if a DAC is really required, it sure would be easier if the Apple site was more informative). I'll wait to hear more, if it seems like a safe bet to take the plunge I'll pick up a Mini in Hong Kong next weekend. Regards, Jeff