A clean installation usually begins with a completely empty hard disk. The advantage
to doing a clean installation is that you don’t carry problems from the
old OS over to the new one, but the disadvantage is that all applications have to
be reinstalled and the desktop and each application reconfigured to the user’s
preferences. You perform a clean install by resetting your CMOS to tell the system
to boot from the optical drive before your hard drive. You then boot off a
Windows 2000 or XP installation CD-ROM, and Windows will give you the
opportunity to partition and format the hard drive and then install Windows.