This is how I got it to work...

[Lost_Tiger]

It seems you have to setup a Games for Windows Live Profile. I got Section 8 to work by going to http://www.xbox.com/en-US/live/pc/update and clicking the Download the Games for Windows Client. After you download, run the file and setup a profile. Follow the setup instructions. Once that is done, login to Games for Windows Marketplace that you just created. Now go back into steam and run Section 8. If all went well a Games for Windows Live window will show up at the top of the screen. I scrolled down this window and clicked "Create a Local Profile", followed the instructions and Section 8 WORKED !!

I will check back tommorow if I can help anymore.