If you want a clean install you will not be able to protect your programs. Your data is no problem as that can be copied across to another disk and then brought back later. Programs are different as when they install they make changes in the registry that won't be present in a fresh install of Windows. Personally I would approach the job by making another partition on the hard drive that you are not going to use for Windows. Copy all the data files acros to that partition. Download antivirus and firewall and any other free progs to this partition. Make certain that you have all the install disks for the programs that you use and registration keys. Access the bios and set computer to boot from CD, put in XP disk and boot computer. Reformat drive for a fresh install, do not select repair Windows. Let XP install and then re-install AVG & firewall and update XP then re-install progs.