Update : below stopped working after upgrading the kernel to version 2.6.18-92.1.22. Trying to find out why 
Update2 : okay I was too fast probably, seems to be working fine after a reboot 
The 2 onboard Marvell 88E8056 PCI-E ethernet on my P6T Deluxe weren’t autodetected by CentOS 5.2.
Got this workaround from the CentOS bugtracker :
# modprobe sky2
# echo “11ab 4364″ > /sys/bus/pci/drivers/sky2/new_id
It works!
There’s a warning of data corruption on Gigabyte boards with this workaround, so better check first and do some more looking if you’re in that category.