Mouse Speed way too fast

Hello.
I only have this problem with the WOTLK client. (I am here to play Vanilla and BC)
My mouse speed is way too fast.
I have it on the lowest in-game, but it is probably 3x times too fast still.
If I slow it more down on my computer settings - then i'd be impossible to use my 2nd monitor while gaming.
-
I have tried changing the mousespeed "0.5" to "0.2" etc in the config file - but it just resets if I click on my 2nd monitor while in-game, meaning it gets way too fast again..

I cannot find anything on the forums regarding this matter.

Anybody that can help me out?