Well, what are you plugged into? If both are 10Mbps then my first guess would be that you're plugged into a 10Mbps only hub or switch =)
The A7N8X Deluxe mobo comes with two onboard NICs, both using different chipsets. One is a Realtek based NIC, and the other is a 3Com based NIC. Make sure you're using a 10/100 hub or switch first, then post back your OS and any other pertinent info if that's not the problem.