Here is a site that you can download a file that will edit your registry to disable the left, right, or both windows keys. You have to reboot after install. It works, I tried it on the left button, now no more annoying windows button!
http://johnhaller.com/jh/useful%5Fstuff/di...Fwindows%5Fkey/ (http://johnhaller.com/jh/useful%5Fstuff/disable%5Fwindows%5Fkey/)
NOTE: As always, look at the file before you allow it to edit your registry so you don't get bad things installed on your machine. I checked the one I downloaded for the left button and it didn't have anything other than the edit for the button.