What they mean (which has been discussed at length over on the Abit USA forums) is that the onboard NIC is on the pci bus. It is not on a 1x pci-express lane as most of the better motherboards NIC's are nowadays. Does it really affect real-world performance? That's debatable, but most likely not.

It's a negative because the pci bus is shared with all pci devices (ie sound cards) and uses a few more cpu cycles, where as pci-express uses less cpu and is not shared with anything else.

Shawn