difference between the models of the MacBook Pro 17" Non-Unibody

A1151: 2.16 GHz Original Core Duo model with 667 MHz Bus, 2 GB max RAM, the ATI x1600 graphics chip, Bluetooth 2.0, and 2 antenna cables for 802.11g.

A1212: 2.33 GHz Core 2 Duo model with 667 MHz Bus, 3 GB max RAM, the ATI x1600 graphics chip, Bluetooth 2.0, and 3 antenna cables for 802.11n.

A1229: 2.4 or 2.6 GHz Core 2 Duo (Santa Rosa chipset) model with 800 MHz Bus, 6 GB max RAM, the NVIDIA GeForce 8600M GB (256 MB VRAM) graphics chip, Bluetooth 2.0, and 3 antenna cables for 802.11n.

A1261: 2.5 or 2.6 GHz Core 2 Duo (Penryn) model with 800 MHz Bus, 6 GB max RAM, the NVIDIA GeForce 8600M (512 MB VRAM) graphics card, Bluetooth 2.1, and 2 antenna cables for 802.11n. The keyboard layout changed with different function keys, and the trackpad is multitouch.

I hope this helps!!