Good idea.
You will need "events" to keep people coming back. Check out what the Apple store does in NY and SFO: classes, presentations, lectures, special promotional events, etc.
Make sure you have a roster of training classes: how to rip CDs, how to make a track info template, organizing your collection, installing Girder, etc.
Maybe get permission from local musicians so you can make compilation CDs and burn them on the fly. Or drop music on people's iPods.
Put in a wireless LAN and run a Media Server, so people with laptops can get a demo version of MC and connect to the Media Server.
Build some kind of large sculptural/video installation that reacts to music to act as a "tourist attraction" - I'm sure you can commission some neat stuff in the Twin Cities. In fact, sponsor a competition in the art schools to make visuals/installations that tie-in with music, and have ongoing exhibitions, all hosted on MC.
Etc.