I've tried searching for this without finding any good answere. Not one of the x- and y-axis problems, but as simple as my mouse sensitivity beeing way too high in every direction. I've got a Razer 3500dpi 1000Hz mouse with the desktop sensitivity set to 1 of 11 giving me what most people would consider a low desktop sensitivity. However, ingame Skyrim I can't pull the sensitivity down even close to what I'm used to. It's so high that if I want to do a 180 degree spin quickly pulling the mouse the same distance I would in another game, I end up spinning around 10-15 times.

Is there any setting in the .ini files, or anywhere else, I could change to lower the mouse sensitivity without having to lower the dpi of my mouse. There should be a way of lowering the sens without lowering the mouse's accuracy..

I've got the opposite problem. I've got a 1600dpi mouse with full sensitivity set ingame and its still too low

I found that I can change the sens in SkyrimPrefs.ini.
I had to change the values to
[Controls]
fGamepadHeadingSensitivity=0.0008
fMouseHeadingSensitivity=0.0008

This setting is only for direct mouse sensitivity, Seems the Y axis is dependant on fps, Ie the higher fps the higher the Y axis sensitivity will be
Its better to cap your fps, either by Vsync or Bandicam, Dxtory if Vsync is causing Inputlag

And manage your Y and X axis independantly, sicne the game does not support a hardwaremouse (its all software driven)

See my topic i made earlier http://www.gamesas.com/index.php?/topic/1258624-possible-fix-for-mouse-issues-related-to-fps/

In the SkyrimPrefs.ini I also changed the fMouseHeadingSensitivity=0.0090 and set bMouseAcceleration=0. I turned the ingame mouse sensitivity down about 3 clicks as well. This made the in game cursor movement more natural for me. I also set bGamepadEnable=0 and bGamePadRumble=0 since I'm not use a gamepad.