Ah yes, changed the resolution, and it started up without that error thing, and I can see what looks like a level editor, now to test to see if it actually works.

-Edit-

Well it does seem that the mouse clicks are a bit off, but I guess that's another problem. Does it get fixed if run in a window? If so, how do you run in a window?

(I'm not sure whether this should go in tech support, or in level editor, so I put it in here since it is the level editor that's not working)

Every time I try to start up the level editor through Steam I get this error: "Runtime Error!
Program: c:\program f... This application has requested the Runtime to terminate it in an unusual way. Please contact the applications support team for more information."

I have an official Steam account, am running it in online mode, can run the base game just fine without changing settings, am running windows 7 32-bit, I have a 2.2Ghz dual core AMD processor (I think), have some sort of ATI GPU, 256MB of visual memory, and 3.75GB of ram.

All my drivers are up to date, I've tried re-installing it, any suggestions?

-Oh, I should probably mention that I haven't unlocked SMW yet, in case that might be the problem.

Hmmmm... I have the same problem with the level editor, I can run the game fine though. Maybe it's the graphics settings?

I'm not entirely sure how to do it, but I saw it posted somewhere else, but it was for the Steam version. You should probably be more specific by posting your computers stats, OS, and what service you obtained Super Meat Boy from.