Windows 2000 Professional

I am trying to unistall Windows 2000 Professional on a Dell Optiplex GX150. Seeing as that Windows 2000 Pro is not letting me format the C drive (all programs have been closed, still get the message saying that I need to close all programs before formatting, however, all TSR programs have been closed) , and there is no accessable DOS shell around Win 2000 Pro to format on, how would I need to go about getting this OS off of the HDD so that I can reinstall Win 98? Would setting the drive as a slave to a HDD with Win 98 on, formatting the HDD, cloning the drive with Win 98 on, and setting back to primary be the best way to go about doing this, or is there an easier way? NOTE: I do not have the recovery CD for this unit. THANKS