That's the decision I would have made if this were my system.
Some types of malware can result in a system so badly damaged that a Repair Install will NOT help!
. Reinstalling Windows without first wiping the entire hard drive with a repartition and/or format will not remove the infection. The reinstall will only overwrite the Windows files. Any malware on the system will still be there afterwards. Starting over by wiping your drive, reformatting, and performing a clean install of the OS removes everything and is the safest action
In case you need help with this, please review "How to partition and format a hard disk in Windows XP
These links include step by step instructions:
"Clean Install Windows XP
"Reformat & Clean Install Windows
"XP Clean Install Interactive Setup
Reformatting a hard disk deletes all data. If you decide to reformat, you should back up all your important documents, data files and photos. The safest practice is not
to backup any .exe files because they may be infected. After reformatting, as a precaution, make sure you scan these files with your anti-virus prior to copying them back to your hard drive. Don't forget you will have to go to Microsoft Update
and apply all Windows security patches.
If you need additional assistance with reformatting, you can start a new topic in the Windows XP Home and Professional forum.
Do you think I need to just buy this directly from Microsoft since they should have the most current copy, or from a software store
As long as you go to a reputable store to buy your disk, you should be fine. And that would be faster that buying from Microsoft through the mail unless you pay extra for speedy delivery.