OK, just to be clear, VirtualBox runs on top of Windows/Linux/MacOS/Solaris "Host" machines. It is not a MS DOS app if that is the DOS you were referring to. One caveat I forgot to mention. If you wish to create a 64bit "Guest" then the Host OS must be 64bit. But you can run 32bit Guests on a 64bit Host. And in another thread JPM or JerWA mentioned a utility for resetting Windows Vista/7 trial period indefinitely. Also, Wine is not a perfect emulator. Some WinApps refuse to run under Wine. I am not sure about VB6 or VB2010.
All in all, VirtualBox is a great idea and from my limited experience with VMware, is much much easier to setup and run. And Free never hurts
Oh BTW, since you have used Ubuntu, you have used Linux. Ubuntu is just another variant or distro of Linux. Other distros include CentOS, Gentoo, Red Hat, Mint, SuSe, etc...