The wireless card has to have n capability. If not, you will be running in a,b,g mode. If the card is compatible from a Core 2 Duo, the enabler allows the card to run a,b,g,n. You can then connect in n mode only with a typical link speed of 270M @ 5Khz. When you run the enabler you will get and error message that your processor is not compatible with Duo Core's. In my case, I missed the n capability by a week or so with my MacBook and did not read the new Airport specifications well enough. It was very crafty writing. I wanted to run my iMac 2.16 and MacBook 2.0 Duo Core with the n draft, but discovered the error message when installing the enabler on the MacBook.
I was slighty perturbed that I was stuck in g land with the router having to run a,b,g mode. The iMac took 20 seconds and was up and running. Sadly, when you run the router in a,b,g,n mode your g speed is degraded. happily the solution was a $ 43.00 Mac Book Pro 802.11n card. I pulled the keyboard off and installed the Airport card. I booted up, ran the Airport disk which enable he driver and rebooted. It noticed the new card on the first boot and I proceeded to install the enabler and it failed. I rembered from my Hitchhikers guide " Don't Panic". I went into the router and set it to N only. As the router rebooted, I rebooted the MacBook. After this, the radio signal quickly went full signal and was running on 802.11 a,b,g,n mode at 270M.
To me, the enabler is obviously in the driver on the new Airport cards because it still will not take it due to the processor, but I swear it's faster than being plugged into the router directly.