Why not put the reformat on hold and use some good anti-virus and anti-spyware software to clean your PC? I would suggest you do all scans in Safe Mode to minimise any virus/spyware activity.
Having done a good set of scans you could then use one of the online offerings such as HouseCall to provide a further bit of confidence.
If you insist on a reformat, you will still need to ensure your D: & E: drives are clean or risk reinfection. However, other than cleaning them you should be able to save all safe data.
For a safe system you need a decent firewall that provides both in and out data transfer protection, a good anti-virus and a good anti-spyware program - all three are available for free, check the downloads on this site. You should also check any CD/DVD/Floppy/HDD that you connect to your PC if it is from an unknown source; additionally stay away from suspect sites!!