First of all, I'm new to the forums, this is my first post XD But I thought this topic was worth creating an account for, and it very well might help out some people.
It's not just logitech that is causing issues, in fact it's not even all logitech that is having issues. And it is more commonly the logitech usb connected devices that are causing issues and not so much the ps2 connected devices.
As for the other fix. My boyfriend tried EVERYTHING with his mouse (logitech) and keyboard (IBM) To no avail. Then he tried removing his saitek game controller and removing the drivers, boom, lag is gone.
So if removing the mouse and/or keyboard is having no effect on your lag issues. Check to see if you have any Saitek hardware, particularly joystick game controllers. Removing the Saitek joystic gamepad and it's drivers fixed the problem for my boyfriend, and he's still using his logitech mouse with no issues :)
Hope this helps some people out.
Edited, Nov 20th 2007 1:26am by obiwills