My S530 is working perfectly in OS X 10.4.8 including all the buttons/hot keys. I have a 20" Core Duo iMac. I'm using the latest Logitech drivers from their website and the Logitech Control Center.
I'm also running XP in Parallels 1940 and have not experienced any of the jerkiness or response issues you are. I am using the default Parallels XP driver because I need the ability to mouse in and out of the Parallels window without a keystroke. I have 2Gb total system RAM with 940Mb allocated to the XP partition. I run Vista RC3 and Xubuntu in Parallels as well with no issues at all.
By the way I just bought the S530 a week ago and I love it!
Last edited: Oct 26, 2006