|You can use ComboFix to clean your computer since you have everything saved already. However, read the cautions carefully. Don't turn it off while it's running unless it tells you to.|
After cleaning the virus off, you can do an XP repair and retain everything that you had.
Borrow an XP pro cd from a friend or buy a new one.
Do NOT reformat and reinstall as you will lose all your current programs and data.
In general you want to do a repair install and NOT use the repair console.
Detailed instructions for a repair install are here http://michaelstevenstech.com/XPrep... He deals with all sorts of problems. He also describes how to create an XP disk with the service pack included easily.
If you can no longer do a repair install or find it too complicated, DO NOT reformat and reinstall as this will wipe you out and leave you with nothing but the operating system. You would have to reinstall all your programs and much of your data would be inaccessible.
Reimage can repair your system even if a repair effort fails if you can get to the Internet. It costs a little but it is well worth it to save your data. It takes about 30 minutes and preserves your programs and data. If you are not happy with the results, you don't have to pay and you can reverse any changes that it made. It's good for a year, there's 24/7 tech support and it repairs XP, Vista and Windows 7 too. More information here http://www.askthecomputerdoc.com/bl...