Installed USB Overdrive 1.4 on my QS 733 (1.5GB RAM, 1 TB SATA, Radeon 9000 Pro) and am using a Kensington Wireless Mouse for Life I got for only $3 at a local store.
Without USB Overdrive, it works like a normal mouse should. If I install it and reboot, it works as it should until USB Overdrive loads--then wherever the mouse is on the screen, I can only move left and right from that point in a perfectly horizontal line. I reset and boot sans extensions, and the mouse works as it should. Trash USB Overdrive, and it works as it should.
I'd really like to use it as I like the wheel and right click functionality.