You could in principle note down everything you have installed, perform a system recovery to set the computer back to the factory, from either the Recovery CDs you made when you first got the computer, or from the Recovery partition on your hard disk (which should not be infected) You would then have re-install the other software that you wanted from scratch, either from the original disks, or downloading it from the internet. This includes updates, drivers etc.
One way of reminding yourself of what software you have is to keep a copy of your infected disk to look at (remove your new disk before looking though).
The other thing you could do is try to remove the virus. , either by returning the computer to a professional to do for you, or by yourself, or sign up to one of the many the forums that exist on the internet who will help you e.g., www.majorgeeks.com
or one of the many others. Volunteers will help you, and direct you to use virus removal tools. It may be a long job and may not always be successful - sometimes the only thing to do is start from scratch (erase your hard disk: try NOT to erase the recovery partition though. If you have lost the recovery partition, and you did not make recovery CDs, HP may supply you with a set of recovery disks if you ask them nicely and give them loot.
Let us know how you fare (in a couple of months....)