Hello there ...
I know in HP computers .. If your model was purchased after january 2006 you can make your won recovery disks.
you use a tool called ( HP CD/DVD creator ) located when you go to Start -> all programs -> System Recovery.
it will take 2 hours and you will be in need to have 2 or 4 DVD's
there is a recovery partition on your system when you restart the computer you can hold F11 on boot, you will log to the recovery program
you will be having two options .. either you can repair Windows or you can make a full recovery which will format everything and reinstall windows.
in your case as long as your computer affected by viruses.
it's recommended to run your viruses scan and incase if there is no luck you can do a full recovery it will take 30min.
All your Data will be lost.
if you don't have a recovery partition and you need recovery disks you can call HP and order for them ( They will charge you for them). (( they will never send it for you for free )) !!