How to increase mouse sensitivity beyond normal limit?

I am not sure a software solution will be ideal (or even possible) here.

Are you averse to bringing your own mouse to work? Many gaming style mice have hardware DPI selectors, which let you switch on the fly from, say, 200 DPI (glacially slow) to 2000+ DPI (your cursor is now on fire).

Something like the Dell J660d mouse can be picked up for around $10

http://www.google.com/products/catalog?q=dell+J660D

and it has the requisite hardware switching of DPI:

Adjustable DPI: 400, 800, 1200 or 1600 DPI with a Click of the Mouse.

Is "Enhance pointer precision" checked?

This enables mouse acceleration - the pointer will move faster at higher mouse-speeds.

It's late answer but I managed to do it in registry.

Go to HKEY_CURRENT_USER\Control Panel\Mouse.

Assuming that your mouse is very slow, then you need to change value of MouseSpeed to 2(to quadruple the normal mouse speed).
Then set the values of MouseThreshold1 to 1 and MouseThreshold2 to 2.

When I tried to set the Thresholds to 0 it was like I have unchecked the Enhance pointer precision so I set it back at 1 and 2. (I'm running Windows 7)

Open 'Registry Editor' in your machine.

Run > regedit

Look for the following key

HKEY_CURRENT_USER\Control Panel\Mouse\MouseSensitivity

Change the 'Value data:' to the sensitivity you require. Restart your machine.

I use a Steelseries Rival optical mouse, you can go on their website and download an engine that let's you increase the sensitivity beyond 'control panel' as well as make some other adjustments, etc.

My suggestion would be to look up the model of your mouse and search for software that can add to or over ride control panel limits.