Mouse Sensivity

To achieve an optimized mouse speed you have to do these things first!
You have to switch off mouse acceleration. You can do this by clicking: Start -> Control Panel -> Mouse, and there you can demark mouse acceleration.
Or you download the cpl_mousefix.reg (remove included).
Now you should set your Monitor up to 100Hz at the resolution you play CS. This is a must for a good sensitivity.
Should you be still at 60Hz, you need a refresh tool; I recommend using ReForce.exe with ATI graphic cards and the driver setup (advanced options) with GeForce cards. Should this option be not available because you are using a new driver version, you need to use the coolbits.reg registry-key (from 7x.xx Drivers) to unlock this function in your driver.
I think you don’t need a mouse driver, besides you are using the features of your mouse like dpi switching or something like that. Drivers simply arise the DPI but a old game like CS cannot handle this high dpi, so forget about it. But it is your decision. I recommend using the driver with Microsoft and Razor mice, but not with Logitech mice.
The best way in my opinion is to simply deactivate the mouse acceleration in the Control Panel and use the following commands for the launch parameters of Counter-Strike: –noforcemaccel –noforcemparms ; You can do this by right-clicking on the Counterstrike symbol at the “My Games” list then choose properties and set launch options.
-noforcemspd use desktop mouse speed settings
This tells HL to use the speed settings you have set on your desktop. Whatever you set in your mouse properties is how it will behave in HL.
This is separate from the "sensitivity" setting in your mouse properties, think of the sensitivity as an amplifier, it can attenuate the movement, leave it exactly the same or amplify it.

-noforcemaccel use desktop mouse acceleration settings
Normally in HL the last thing you want is acceleration. Sometimes the HL no-acceleration control won't work because the mouse or its drivers are too different.
This switch tells HL to bugger off trying to manage the acceleration and whatever you have set in the mouse properties for the desktop is what will happen in the game.

-noforcemparms use desktop mouse buttons settings
This setting tells HL to use whatever button assignments you have set in the mouse properties. You have to make sure each button has a letter or function-key assignment appropriate for the game.
Normally HL forces it's own set of button definitions onto the mouse and when you return to the O/S all the buttons return to your operating system setup. This switch turns that off.
Unfortunately, this means that if you press a button set up for HL on the desktop or in some other application then your mouse is going to try and send HL letters or commands to that application.
For example, with a Logitech MX310 you can set the right-most little-finger button set to do a reload or "r" letter.If you are in notepad however and accidentally hit that button, you'll see "r" suddenly appear in the document.Still, that's ok, you can adapt to it and it makes the mouse play very well in the game.