Hands down easiest to double box on 1 computer?

[doubletake]

What is the easiest program(can be hard, just needs a very detailed tutorial) to double box on 1 computer.

Thanks much

[beyond-tec]

http://solidice.com/keyclone/

Thread about Keyclone:
http://www.dual-boxing.com/forums2/viewtopic.php?t=883

Tutorial (step by step with pictures):
http://solidice.com/keyclone/tutorial/index.html