Hi Jim,
I agree that we have very similar set up. I have two desktops, one of which is a server, and two working laptops. I back up A.C. into 2 portable harddrives, one of which to be taken home. My A.C. database currently is about 11 GB (guessing from several lab reports, imaging reports per patient; each has to be scanned as PDF format and imported to A.C.) I am not aware of any thumbdrive with such large capacity. What is the size of your database ?