d-link usb device seconded: I used one one a desktop for a while and it worked great.
And if your computers still don't see each other, check the firewall settings - I recently had a hell of a time figuring that one out.
If you're serious about the bass, the real deal all tube SVT is unbeatable. Your bass will sound like a bass should sound.
And a 4x10 cab should be plenty big for most venues. You can get the SVT Classic head and 4x10hlf cab for under $2000 new; it's still a pain in the ass, but not as heavy or ...