If you are going to completely reformat your hard disk, I would recommend making a list of things you want to have after the wipe. Take into account that the brushes you have installed for PS are files, you'll need to find those and save them in a zip. For example a list I might make:
o System drivers and fixes
o Win Theme Settings
o Registry (for reference)
o Patches, fixes
o Messenger logs
o My Documents (if you use that folder // or similar)
o Plugins for various programs
o Export messenger contacts list (if your client saves it locally)
o Your artwork (sigs, renders, icons, cursors etc)
You might also want to compile a list of links to where you can retrieve patches if you no longer possess the patching program. Regarding Windows, the chances are that the problem you are encountering can be fixed by using a program such as adaware
. I'd advise you run virus scans and look at running this before reformatting. If you can't even get into windows at all, you might want to consider using a secondary hard disk to install windows on and fix the infected one from there (has worked for me in the past).
Hope this is of some use to you dude and good luck fixing it!