K7V Dragon PXE network boot support

OK, so the K7V Dragon is a fairly ancient Mobo by today's standard,
but with the BIOS claiming that it canboot from LAN, and an onboard
NIC, I'd have expected it to do the right thing.

I've got one I'm trying to set up as a thin Linux system, however,
nothing I can do will get it to boot over a LAN. Did Soyo drop the
ball on this, or is it as simple as getting a Bios flash.

Any ideas?

Thanks in advance