
That promo worked but Microsoft, it turns out, is extremely stingy. It's a 7-day trial membership and so basically all it lets you do it play multiplayer online. You can't get the free Games with Gold game, so I missed out on Dust: An Elysian Tale. That sucks but I do have it on my computer already thanks to the Humble Bundle. I would've have rather played it on the 360 though.
They also don't let you use the online storage with a trial membership. Thankfully, my wife found a way to transfer the saves to our harddrive, so at least we'll be able to continue with Gears 3. I just wish Microsoft would tell you these things. We had to do all this digging online in forums to figure out what came with the trial membership and that's how we found out how to move the saves too.