Yeah, seems as if Jamestown is the only one you can activate on Steam. I still can't decide if I want to pull the trigger on anything just yet or (as damn near everyone else mentioned) wait for the Steam sale. I think MW3, Saints Row 3, and Skyrim can hold me a few weeks..hah...
Sorry 'bout the delay in responding. Woke up, found deal, posted, drank coffee went to work..haha