Xbox or PS3?

You can't go wrong with both/either. PS3 might be a little better for your case, but I voted 360 because I like the controller and the infrastructure better. For *me*, that would be my choice.

If you want baseball games, then PS3 is your only option. MLB The Show is the best baseball sim (by a huge margin) and only on PS3. I don't even think the 360 is getting a baseball game this year.

I'd say the decision of which console to buy depends on a couple things:

-- are you interested in the exclusives that a particular platform offers?
-- do you have a lot of friends who own a particular platform and who you want to play online with?

I personally don't play online much, so I went with the PS3 because it has a lot of great exclusive games. As number1laing notes, one of those exclusives is a high-regarded baseball simulator, which might be sufficient reason for you. There are various lists online of the best games exclusive to each platform; take a look at those, read some reviews, and see if they interest you.

I'd like to setup a gaming corner this year so I intend to buy a PS3 next month. It has the game that I'm interested in - Grand Turismo. Thus, voted for the PS3.

PS3 but the lack of backwards compatibility in the upcoming PS4 is a horrible business model. PS3 dominates as a bluray player/media center as well.

My vote goes to the 360. Gears of war and Halo take the cake in my book. I do have to admit that PS3 seems to be the ticket for sports games though. Id rather shoot aliens than baskets so you know...