SPE comes with wxGlade, an interface builder, and XRCed, an XML/interface file editor, as well as some other useful things. The best way to get and update SPE is using subversion. On Windows grab TortoiseSVN and on Mac OS X I recommend getting the version distributed by CollabNet.
Go somewhere on your hard drive you want to keep the IDE, such as your home directory. Checkout SPE using the command line client:
svn checkout svn://svn.berlios.de/python/spe/trunk/_spe
Once that’s checked out, run SPE by going in the _spe directory (DO NOT EVER RENAME THIS DIRECTORY) and run ‘python SPE.py’. You can update to the latest version of SPE now by going into the _spe folder and running an update: