I can run 4 on my amd 3200+ with 1.5gigs of ram ati x800xt 512mb gfx card. runs fine on that setup with AHk script I wrote. keyclone works good too.

my laptop is a

dell inspiron I9300

intel pent m 2ghz with 1gig of ram geforce go 6800 can run 3 accounts just fine. Im going to upgrade to 2 gigs of ram and see if I can handle more.