So you want to enable Compiz-fusion with your dual head monitors? Here's the deal, compiz runs at a maximum resolution of 2048 x 2048. This is where most people run into trouble. You can't run both monitors side by side because it exceeds the maximum resolution.
Here is what to do:
1. first off go to System>Preferences>Display
2. un-check "mirror screens"
3. stack your 2 monitors on top of each other. Just click and hold on one, and move it above or below the other.
4. then go to preferences>appearance>click on the visual effects tab, and enable extra effects.
5. If you have Compiz installed, it will work right away.
