Portable GeoGebra
There are portable versions (that don't need Java installed) of GeoGebra available for various platforms here:
http://code.google.com/p/geogebra/downloads/list
We recommend this version for Windows:
http://www.winpenpack.com/main/download.php?view.647
Note that Mac OS X has Java installed by default so there is no need for a portable version. The regular version is here:
http://www.geogebra.org/download/
