yeah, Game Maker 7 worked fine for me on Windows 7 Beta back in the spring time. It did have a weird thing where when you were importing media it took longer than it needed to but it was fully functional.
Also there is a Game Maker 8 alpha/beta build out there, it was released in july of this year, you could try it.
When Game Maker 8 comes out it is supposed to be considered a "commercial game developement tool" although it doesn't seem like they are changing that much. I have XNA for free via my college anyways so whatever
