Put installation disk one into the cd player and restart the computer. When the menu comes up choose Install Windows. If the menu doesn't come up and Windows opens as usuall you'll have to go into Setup and change the boot sequence to cdrom first. To do that restart the computer and one of the start screens will say "To enter Setup Press" such and such a key. You may need to be very quick to catch it. I have a Dim2300 but have only entered setup once. Then exit Setup and save settings. When it boots the Setup menu should be there. Choose Install Windows over repair. You'll need to change the boot sequence back when your done. Your ProductKey should be on your case, have it handy, but in most XP installations the PK is stored in CMOS and you won't have to put it in. I did recently do a fresh install with an HP and that was the way it worked.