Have you updated the PXE rep? That sounds like a silly question but would be one simple explanation.
Is the Hardware ID on windows the same as the hardware id in the inf file?
I have a very similar problem - i can build all our HP models exept the DC7600 !!! Again tried all the drivers from HP with no luck. The puzzling thing is they are all supposed to use the same NIC. (broadcom netxtreme)
Are all your BIOS setting correct? - Sata emulation should be off, etc.
Are you using the n1000325.sys and .inf drivers? I also included all other drivers in the "Driver depends" box. My DC5800 worked fine. However I'm am still having a SATA issue. I didn't see a place in bios to turn of SATA mode.
well I scrapped my current PXE deployment, redeployed with the drivers and now it is working again...thanks to all that replied!