F8 is not the correct function for re-setting the computer, that only takes you in to safe mode. If you can remember the date when all was functioning properly then go: Programs-Accessories-Sytem Tools- System Restore.
Alternatively if you know the name of the virus then go to run and key regedit. That will take you to the registry editor and look for the virus by name BE CAREFUL IF YOU HIT THE WRONG KEY YOU WILL HAVE TO RESTORE THE ENTIRE OS!
I gather you have had the machine a year which means you may not have been provided with installation disks in which case you should have made a back-up disk of your system!
In the event my suggestions don't work then you will have to buy installation disks from the vendor or buy your own copy of windows - ouch!