ummm, I don't know, it just does. That's the resolution my screen is always set at and I just started out by downloading the Trial version and installing it. I went into the game to play mostly to make sure it did play, then back out again to this site to buy the game. Waited to get the code then went back in, put the code in and started playing.

I didn't actually DO anything to get it to play in that resolution though, it just did.

Edited to add:

Just double-checked to make sure I had typed in the correct numbers for the screen resolution. Yep, it says 1280 x 1024 then below that it says Landscape. I do have a rather old monitor though, maybe that's why?