I had the 5100 AGN adapter installed in my Dell Studio 1737 but I had Vista Home Premium 64-bit and Windows 7 64-bit installed on it with no problems.
Did you try downloading the drivers from Drivers & Download enter your service tag, then save the drivers to your desktop. Go to device manager, right click on the 5100 AGN adapter, uninstall, then tell it to uninstall all software with it.
Restart your computer.
Now install the drivers you saved to the desktop.
After you have it installed, check your settings and see it they match mine.