I do hope you have an antivirus solution running?
If not, I would recomend downloading the latest version of Avast, installing it, then running a scan at start up and then in safe mode.
Also, patch up windows and enable automatic updates for protection in the future.
You might also like to run a firewall [Comodo] and Antisyware[Windows Defender]
Also, be wary of inserting stray USB drive into your system. Depress Shift before connecting the drive to prevent Autorun, and hence infection. If you do need to run USB drives between multiple systems then I would suggest you buy one with a write protect tab. That would reduce the chance of infection from PCs where the files are being read only.
Read: *www.precisesecurity.com/files-process/2008/11/09/chrome-exe/
If you are keen on reinstalling the OS, you will need the original windows CD.
=====Software======
Avast: *avast.com/
Comodo: *comodo.com/
Windows Defender:
www.microsoft.com/windows/products/winfamily/defender/default.mspx