If he has the Core Duo, which I believe he does, than the enabler will not work as the hardware is g-only.Yes, you can do three things. Get an N card from a C2D Macbook, get the N Enabler from Apple (US$1.95 download), or find a cd that came with a Airport Extreme N and get the N Enabler from that.
If he has the Core Duo, which I believe he does, than the enabler will not work as the hardware is g-only.
There is no mid 2006 MacBook, only an early 2006 (Core Duo) and a late 2006 (Core 2 Duo). If you have the early 2006 model, the enabler will not work and I doubt that you can put a newer card in.