Just found a short tweak guide (primarily for MP, but you can use this in SP to improve your experience, too). Check it out.
Woohoo! More tweaking: This one's to help with the mouse lag.
Yes, it's a pain to have to type in a command every time you start the game. I haven't tried this yet, but I'd guess that there's some way to add the command to shut off acceleration to the config.txt, we just haven't found it yet.