dual optical has two lasers but only one works at any given time, whichever one is getting the better reading.. they are lower res than the mx sensor.
all mx mice give the same performance including the wireless.
Athlon 1700+, Epox 8RDA (NForce2), Maxtor Diamondmax Plus 9 80GB 8MB cache, 2x256mb Crucial PC2100, Geforce 3, Audigy, Z560s, MX500