Odd ... HP doesn't have anything other than a firmware update for your machine under Vista OS and very little under XP - none provided for ethernet. Strange. I would use something like PC Wizard or Everest to scan your pc's components and you may find your ethernet manufacturer/model i.e. broadcom, intel, gigabit, etc.
Then you can probably find drivers at the respective manufacturer site.
Found this link that says the ethernet model is Intel 82562GT 10/100 Mpbs Fast Ethernet
This might be the link for the Intel 82562: http://downloadcenter.intel.com/Prod...D=998&lang=eng