if you want to just get a quick taste of multi-boxing, get a few 10-day trials from wow and a copy of keyclone or AHK (to be fair). i suggest mages or some other caster as your first group... easier and more fun blow stuff up

i can triple box on my old crappy laptop (1.5GHz, 1G RAM, 64M grfx) and still get 24 fps in SW. (800x600 each windowed)

difference between keyclone is ahk.. keyclone costs $10 once while AHK is free. keyclone requires little to no setup, while AHK has some pretty extensive macro programming.

there are threads on both here in general