I have upgraded from Windows 2000 Professional to XP. I now want to wipe out my hard drive and do a clean install of 2000 Professional. I am studing to be an MCSE and need to work with W2k Professional and Advanced Server. I thought I could look at XP and then uninstall it to go back to W2K. When I run the FORMAT C: command at the command prompt, it tells me the the volume is in use and the format cannot be done. Does anyone have any ideas?