I like Virtualbox myself. It's just more flexible than Virtual PC. It's also free.
Before dinking around in the BIOS I'd try installing and using Virtualbox. Maybe the virtualization extensions have been enabled already. If not reboot and dig around and you'll know it when you see it. It'll either have 'virtual' or 'VTx' in the name. Once you get a blank VM booted you can install anything (almost) on it like you would a regular computer. Windows 2000 or XP, if you have a license, should be fine.
Is this old game a 16 bit Windows game or just something that ran in a DOS shell? If it's an old DOS program then you could try running it on the FreeDOS OS.
Or, now that I say that, if it is DOS you could skip the VM and just use DOSBox:
http://www.dosbox.com/