I'm trying to configure quake live on two different PC's so that my sensitivity feels the same on both of them, I have the following questions though:

*EDIT* Putting answers below so other people can see answers to the questions.

1) Does resolution have any effect on Sensitivity?

No, Resolution does not have any effect on the Sensitivity. Feel might change depending on the Resolution and FOV, but sensitivity will not be affected



2) Can I use this formula (Sens*DPI must = 2000) to standard my sensitivity across different PC's, so with a 400dpi mouse my sens will be 5, am I correct?

Yes, this is correct.

The best way to have the same in-game mouse sensitivity on two different pc's is to do the following

1) Set m_cpi to the DPI of your mouse
2) Set in_mouse "2"
3) Determine what your CM/360 and let this = x
4) Invert the value above, so 1/x or just do 360/(required CM) and that will be your sensitivity
-Keep in mind that this will only work with default yaw values (afaik)


Setups:
-PC (Main)
- Mouse DPI: 1000
- Sensitivity: 2
- Windows Sens: 6/11 (Acceleration off)
- Quake Res: 1680x1050

-PC (Secondary)
- Mouse DPI: 800
- Sensitivty: 2.5
- Windows Sens: 6/11( Acceleration off)
- Quake Res: 1900x1080