You need a server version of OSX to work, I think 10.6.2. I was screwing around with it for iPhone dev as an ultimately futile experiment. And to install 64bit clients on VirtualBox you need to have VT-X, which your CPU doesn't have. You'd have to use W7 32 or XP 32.
I don't know if that's true with VMWare, but you get a lot of software there for just giving them your email address!
Jim