For the *best* experience download VMware Server, its free to download but requires registration to use.
Or try QEMU, but make sure you get the kernel accelerator module.
Qemu is simpler, but is all console based and it is 100% open source. Vmware is rather large, takes quite a few steps but has a graphical UI and is feature rich.
Some notes I wrote on the above
virtualization and emulation choices