OS X :: File Sharing Wirelessly Over Airport Extreme?

I am trying to move files between one Mac and another wirelessly. They are both connected wirelessly to the Internet with an Airport Extreme Base Station (newest version).

It seems to me that the files are transferring slowly, as if they are transferring at Internet connection speeds rather than computer to computer speeds.

The way I am connecting them is by clicking on the other Mac's name from the Finder and then connecting to it. I have file sharing turned on on both computers. I then am dragging the files from a local folder to a folder on the other Mac.

The computer I'm using is a 13" MBP with wireless N, and the other computer is a 17" iMac Intel Core 2 Duo, which I believe has a slower wifi version (maybe g), which I could upgrade to N if I pay Apple $1.99 (I never did, but I remember reading about that a long time ago). Anyhow, even with the slower connection, I still should be getting faster speeds I believe.

Right now, I am trying to transfer a folder with 209 GB of files and the estimated time to complete was at first 45 hours and varied a lot until it stabilized at 30 hours. I canceled the copy until I can find if there's a way to make a faster connection?

I may end up just going about this a different way as I realize there would be faster ways, but I'm curious for future reference, as well�is there a way to tell the computer to route the data through the router rather than the Internet, or is that what it was already doing?