Yes, you can test drive Compiz-Fusion with the SL 5.0 GNOME LiveDVD, and KDE Desktop Effects with the SL 5.0 KDE LiveDVD.
For details of using Compiz, see the Compiz-Fusion Wiki (http://wiki.compiz-fusion.org/
) for instructions on using the various plug-ins. Scroll down the above-mentioned page to the section titled Plugins. Try them out to find out what they do.
For details of using KDE 4.* desktop effects, see the KDE Web site, for example http://www.kde.org/announcements/4.2/desktop.php
(look for sections titled 'The Window Manager' or 'Desktop Effects'). If you go to Kickoff > Computer> System Settings > Desktop (or whatever it is: I am on a Windows box at the moment), click on Enable desktop effects
and then click on the tab All Effects
you'll see a list of the effects which you can select, and the keyboard shortcuts for launching them. Try them out to find out what they do.