Yes, wrong forum. However, I will answer your question.
You can't change it. That feature is there for a reason - mouse acceleration increases pointing precision. Apple didn't just throw in the feature, they have done quite a bit of research on human interface design. Windows also has mouse acceleration, but it is on a linear scale. Apple's mouse acceleration is not linear, it's some kind of exponential scale that maximizes accuracy. If you aren't used to it, you'll have to get accustomed to it. It shouldn't take too long. You might want to try a little utility called MouseZoom (look for it at VersionTracker.com) to get a greater range of tracking speeds. Many people find Apple's standard mouse preferences don't allow for fast enough tracking.
I've switched mice many times. Every time I move from one mouse to another, the speed and the way the mouse handles will change. It is frustrating at first, and many times I've wished that I had never bought the new mouse, but once I get used to it, I'm happy.