jamyskis: I've bought 11 off Steam, although all of them bar Fable 3 have been cheap €2-3 indie affairs. I've spent about €25 in total on Steam. I bought 4 from GOG for about $15, I also bought Two Worlds 2, Tiny and Big, DCS Black Shark, Scania Truck Driving Simulator and a couple of others for around €80 in total.
Oh, and if it counts, I bought Goldeneye Reloaded for the PS3 for €30, plus a shedload of PS1, PS2 and PS3 games from a car boot sale yesterday. Also grabbed a copy of Jane's WW2 Fighters there.
FYI, having been bitten by Fable 3 PC already, the auto save corrupts pretty easily, so after you've played 4 hours or so go make a manual save (do this with the Gear thingy in the wall of the map room/main room in your Sanctuary and choose Game Management instead of QuikSave, use one of your blank mannequins for the save). This way if your auto save corrupts you can simply delete it and use the old manual save (thus only losing part of a play session).
Also, be aware you have to manually download Traitor's Keep and Understone DLCs by using the in game client (though I had to sign into the standalone client after queuing them up). All the game codes get redeemed this way. There's also quite a bit of free stuff you can get by going to the in game store in your Sanctuary.