Here's my temporary setup:
It's a software/hardware hybrid setup, as I do a lot of actual recording, but for electronic music, 90 percent of it is created on my computer in Cakewalk's Sonar 7 Producer edition.
There is very little more than a good program required to create electronic music. It's really up to the producer if he wants to have an extravagant setup or not, but it is in no way required.