When I purchased my computer it came with the OEM version of Windows XP Professional. Operating system I have had several viruses which has caused me to have my C: drive reformatted and then have all of the programs and files that were in-place, prior to the virus, reinstalled. If I get the full version of Windows XP Professional and then get a virus after initial installation, will a reinstallation, without reformatting, correct the problems and reinstall all of the codes that other downloadable software require? Also, can the full version of Windows XP Professional overwrite the OEM version without having to reformat (leaving all of the programs and files in-place)? I’m not ready to upgrade my home computer to Vista or Windows 7 at this time. Do you have any constructive suggestions?