First of all whats the difference between Hardware and software render? Ive heard that Hardware uses your gfx card right? so does software just use your cpu?

also isint software supposed to be faster? because im rendering a scene and in software it took about 20 seconds per scene but in hardware it was only 7 seconds.

my pc specs are Amd 64bit 3200+ processor and a nvidia geforce 7900. and 2.5gigs of ram