Posted 13 March 2010 - 06:27 PM
Are you referring to a dial up modem (that cant be found) or a high speed modem for DSL or Cable?
I checked the Compaq driver page for XP for that model, not many drivers listed.
This driver is on the Vista side, for high speed connections (not dial up) its listed "» Realtek RTL8101E Family PCI-E Fast Ethernet NIC Driver"
You may have to contact Compaq directly for support for drivers to downgrade, some newer machines never had drivers for XP, some drivers work for both, but because Compaq didnt sell you the machine with XP, they dont have to have compatable drivers.