iPod Software 1.0.4 (and later) includes enhancements for iMac (Flat Panel) computers. If you are using iPod software previous to 1.0.4, you should upgrade to the latest iPod software.
Verify that your iPod is up to date by downloading and running the latest iPod Software Updater available from the Apple Software Downloads Web site (http://www.apple.com/swupdates/).
For more information on how to find out which software version is installed on your iPod, see technical document 60984: "iPod: How to Find Software Version."