Yes, as long as you can access the BIOS and change the boot sequence to allow the system to boot from the CD drive. Once that is done, just insert your installation media in the CD drive and then restart the computer and follow the onscreen instructions.
If your operating system is XP, and you have your Windows XP CD, good illustrated instructions for a clean install can be found here:http://www.winsupersite.com/showcase/wi ... _clean.asp
Read instruction #3, and then skip over 4, 5, 6, and 7. Begin with Step-by-Step: Clean installing Windows XP (Interactive Setup).
If you have the computer manufacturer's restore disk(s) rather than an XP disk, follow the directions that came with the restore disks. (Instructions might also be on the disk label).
Before you begin, download your choice of anti-virus product to CD, or have a purchased installation disk ready. As soon as you've finished installing your operating system, then install your anti-virus and check to make sure your Windows Firewall is active. Do this prior to going online to get all needed Windows updates for your system. If you take your system online before it is properly protected, it will very shortly become infected.