I am using Oracle VirtualBox to install Ubuntu 10.10 on my Windows computer at home.  The nice thing about VirtualBox is that I can use it to run another OS while I’m using Windows.  Of course, if I decide to get rid of the ‘virtual OS’ then I just delete the virtual machine from within VirtualBox and tell it to erase all the files.  Presto, I reclaim the disk space used by the old virtual machine.