During the #PPCChallenge I've been using a Logitech G MX518 mouse (which I also use on all of my modern machines). However, I've been encountering some weird cursor jumpiness issues in Mac OS X Tiger and Leopard.

It turns out, these OSes have some issue when dealing with mice that have a fast reporting rate (like this one). All I had to do to fix it was connect it to a PC running Logitech Gaming Software, and change the reporting rate to 125 MHz. No more jumpiness, and I can aim in #UT2004 now!