boot with -v you should see something like below. If not your card did not initialize properly.

Try copying the Vanilla S/L/E/IONetworkingFamily.kext to your Extra/Extensions


Sep 23 08:47:03 localhost kernel[0]: Intel82566MM: Ethernet address 88:88:88:88:87:88
Sep 23 08:47:13 localhost kernel[0]: ring desc success: size->4096, virtual:5d727000, phy:190b9000.
Sep 23 08:47:13 localhost kernel[0]: ring desc success: size->4096, virtual:5d741000, phy:190ba000.
Sep 23 08:47:13 localhost kernel[0]: configure tx tdlen->4096.
Sep 23 08:47:13 localhost kernel[0]: configure rx rdlen->4096.
Sep 23 08:47:17 Mac-Pro kernel[0]: Intel82566MM info: Link is Up 100 Mbps Full Duplex, Flow Control: RX/TX

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Motherboard: Asus P5E-VM DO AMT configured (can be powered on/off remotely) Processor: Intel Quad Core Q6600 @ 2.4GHz GO stepping. Memory: 4GB OCZ - OCZ2P10004GK 1000 MHz; Graphics/Video: Dual Head XFX NVIDIA 7900 GTX 512mb flashed to QUADRO FX 5500(Thanks to Aquamac); Display: Dual Dell 2007WFP & New Dell 2707WFP Main Monitor; Harddrive: (1.) 500GB WDC5000AAKS - (2.)500 GB Seagate ST3500630AS SATA; Optical Drive: DVD DHQ6A1L : Network: Built-in Intel 82566MM running on 32/64.