It would appear that HP only has drivers, found HERE
, for Vista and Windows 7. The only other alternative you have is to see if you can figure out what type of modem it is in the computer. I've looked over the specifications for the computer and it doesn't appear to provide any specific vendor details for the computer.
HP does provide information HERE
in regards to downgrading from Vista to XP.
In order to figure out what modem is installed, you can use either CPU-Z
to take the guess work out for you.