This is what I did to fix my mouse acceleration, I had so many problems with it but I think I found a solution.

Permanent fix:
Download the fix: http://donewmouseaccel.blogspot.com/2010/03/markc-windows-7-mouse-acceleration-fix.html

How to use it:

Find the display DPI that you currently use:
Click Start, click Control Panel, select Appearance and Personalization, select Display.
See if you have 100% or 125% or 150% selected.

Open the ZIP file at the link above.

Select the REG file that matches the DPI% you use and Double-click it.

Answer Yes, OK to the prompts that appear.
(See below for non-Administrator account use.)

Reboot or Log off to apply the fix (you have to reboot or Log off).

Enjoy exactly 1-to-1 mouse to pointer response!

Minor Fix (gets rid of noticeable acceleration, but it is NOT 1:1)
Step 1:
Disable Enhanced Pointer Precision
Go into Window -> Control Panel -> Mouse
Under Pointer Options
De select enhance pointer precision

Step 2:
Go to Control Panel.
Ease of Access
Ease of Access Center
Click ‘Set up Mouse Keys’
Change acceleration accordingly:

Step 3: (Optional)
At this point your mouse acceleration should be gone, however if it is not gone try disabling vertical sync (vsync) in your game video options.

That worked for me. If anyone has any other ideas please feel free to share them by commenting on this thread!

Windows XP:
Apply the CPL Mouse Fix
The file can be downloaded here: Mouse Acceleration Fix
Unzip the archive and double click on the file inside.