Unfortunately, I can't seem to get the mobo to detect the card in favor of the onboard graphics. When I boot into Windows or Linux, Windows does not detect the hardware, and running lspci on Linux does not show the card.
The board you have is really old. At the linked HP site, it specifies PCI-Ex1 written on the mobo when defining the slots. While the video card is fairly old also, your mobo may not support PCI express 2.0 x16 slots. I have some boards that are newer than yours that dont work either.