Dim-Ize,
there are two versions of the 4th side, so make sure you pick the one with the icons you would prefer. Both of them only add the 4th side and leave everything else alone.
You also might want to check out Polen's Vista Cube with 4 sides.
http://forum.ppcgeeks.com/showthread.php?t=12798
And don't forget, GPS comes in a month or so, too! Now to figure out how to integrate GoogleMaps into the Cube...hmmm.