Some of the things. I'v read about VPC.
It's a Virtual PC solution--- a complete PC, emulated in software, inside your regular operating system. The VPC thinks it's a fully normal standalone PC, and all apps running on the VPC think likewise, even though the VPC is really just a memory space and special software running in your real, physical PC alongside your normal apps.
When you set up a VPC, you can specify how much memory it will have, and whatever goes on inside the VPC normally cannot--- *cannot*--- reach out to the main PC to take over more RAM or CPU horsepower than you allocated. In fact, the VPC can be totally isolated from your real PC, if you want it that way; or it can connect via networking, just as if it were a separate PC. In any case, a VPC can work as a kind of self-contained sandbox where you can run voracious or even dangerous software with essentially no risk to your real PC. I use a whole fleet of VPCs for testing and research on my PC; not only for trying apps I'm not sure I want on my main system, but also for running Linux and other versions of Windows inside my main copy of XP. It's very cool technology.
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