Looked a cobalts, don't like them.. since they got bought out by Sun there support has gone downhill. I have a cobalt for some websites I host and they started out great but are now a hassle, and slow compared to any other server theses days.. shrug
Let me take that back.. There free support has gone away.. If your willing to pay $99 just to talk to a cobalt rep its great...
I talked to the people and they say its a fully patched redhat 6.2 install, with a 7.1 upgraded coming within a month, I can install any package I wish, with a small warning that any package that might change the mail/httpd setup might break the web control panel which is totally understandable...
I don't know though.. Not totally sure what a "virtual server" is... I know I would be sharing a single computer with multiple people but can they access my files or anything?