Well, here's a FREE UPGRADE to anyone who wants to experience silky smoothness like never before in their FPS game without the latest hardware! MX-518 owners will love this! It works with most standard mice - the degree to which will be determined by the quality of your mouse hardware. This is not new, but shockingly, very little is known about these special tweak files. If you're serious about your game though, then this is a 'must'. If you've already got one of the latest top-of-the-line (corded) mice from Razer, Logitech or Microsoft, then you are probably are already running at 1000Hz (or are capable of it). Razer has been doing it for a while it fact. Mice are very personal things however, and we all have our favorites for our own personal reasons. But unless you have one of the newer mouses available, then you are likely just running at only 125Hz! After the tweak, you will be running anywhere from 500-1000Hz and will both SEE & FEEL a very noticable difference instantly! Your mouse will become much more responsive over shorter distances as it's position is being read at a much higher rate. This is accomplished by raising the USB port speed to 1000Hz from the standard 125Hz. It is completely safe and harmless and it aslo completely reversible via the same software tool. It might take a bit of getting used to at first and you may even need to make a few sensitivity adjustments as well.
The original tool was released by Techconnect Magazine for Windows XP & Windows 2000 - it is called: "USB Mouserate Switcher 1.1". It stopped working for XP however if you tried to apply it AFTER installing Service Pack 2. Surprisingly noone updated it! It was driving me crazy because once you've experienced 1000Hz, you really don't ever want to go back to 125Hz.
I searched and searched and searched and just when I thought all hope was lost I stumbled upon a newer utility that DOES in fact work with XP SP2! It's called "USB Port Tweaker".
You can download the utility here (the referring page for the file is: http://www.esreality.com/?a=all&user_id=24555)
To confirm both your existing and new speeds, you can download a program called "Mouse Rate Checker" from here (the referring page for the file is: http://tscherwitschke.de/download.html)
P.S. 1000Hz can be accomplished in Vista too - here is a Google link for more information