When you mention Virtual PC that's Microsoft's virtualization solution. Similar to VMWare and Open Source VirtualBox. It only looks matipid sa angulo na once you're able to set up a virtual machine, you can backup the virtual hard drive somewhere else at kung may nangyari sa ginagamit mong VM, just copy back the backup and everything goes back as a fresh install. Yun ang natipid mo -- time -- dahil na-setup na before. As for cost of investment? You still have to pay a separate license when it comes to the guest O/S as well as the commercial applications you are going to use inside the VM. As far as gaming is concerned? Forget virtualization. There will always be some performance penalty.
If you are referring to thin clients that's a different animal.