Is this for production, business use or just for personal testing and messing around?
TFS2010 is a bit of a beast, especially when running SQL on the same box, and you'll need an additional VM runnign concurrently if you're planning to use the build server feature (it should not be run on the TFS server itself).
If you have a piece of hardware that you can dedicate to the task, look at running ESXi, Microsoft Hyper-V server, or XenServer, then running the VMs on top of that. They're all free, and installation is straight forwards as long as the hardware is compatible.
If you absolutely have to run on top of an existing Windows installation, then VMWare Workstation or Virtual PC will probably suffice. Outside of this, there's a good feature comparison matrix here.