Mouse smoothing is a default in all Windows versions and up until Windows Vista there was no option in the GUI to turn it off where I know the option at least exists up until Windows 7. IN Vista+ you go to mouse settings and untick "enhance pointer precision(LOL?)". Otherwise you will want to use CMouse (which I use for Windows 7 too, just because there is an option for it, which makes me think maybe the GUI option isn't 1:1).

1.) Download CMouseFix.
2.) unarchive it.
3.) Run the .bat file for your operating system.
4.) Log off/reboot.