I DL'd from Gamersgate.... don't like steam. You have a code, check on your Gamersgate page... purchased games I think its called.... something like that.
EDIT: To be more specific, after logging into Gamersgate click on "My Games" on the left side of the screen; a window should open with your purchased games; scroll down to SF; your serial key is right there.
zz
Thanks again zz
WK