since you can boot to hirens, you may want to create a new account with administrative allowances and then delete all the other accounts,
the very best thing to do would be to reinstall the entire os.
http://support.hp.com/us-en/drivers#Z7_M0I02JG0KGVO00AUBO4GT60080
go to above website on a working pc and download the various drivers that will be needed, and if the pc has not been updated in 7 years then it will be very outdated as far as microsoft security updates.
so therefore before downloading any drivers do the following
1. ensure that there is a antivirus installed
2. Courtesy of Tricky 300
Before you install SP3 read this article…
http://support.microsoft.com/kb/950717
…and if your PC is an HP Pavilion, Presario or Media Center and has an AMD processor you need to install this patch before installing SP3…
http://h10025.www1.hp.com/ewfrf/wc/softwareDownloadIndex?cc=uk&lc=en&dlc=en&softwareitem=pv-60484-2
…to find out if you have an AMD processor...
• Hold down the Windows key (between Ctrl and Alt) and hit the Pause Break key
• Your processor type is shown in the Computer: section
Then install SP3 by downloading and running from...
http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=24
…you can ignore the text that says that it is for network installations and also ignore the text advising Windows/Microsoft Update if only updating one PC.
Reboot twice after installing.
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3. go to start/all programs/ top of column go to windows updates
you will be asked if you want to upgrade to microsoft updates say yes, follow prompts, you will have to have a few active x installed, and a few updates installed after that then you will be able to scan for updates and install them, this will be a lengthy process.