While Guide itself may not make much use of a dual processor setup,
Windows NT, 2000 and XP Professional all do. The main advantage, I
believe, is that the disk, screen, and communications I/O can be
offloaded to the second processor, leaving more CPU cycles to the
application using the first processor. Windows 95, 98 and ME detect but
do not use the second processor at all.

I run dual PIII 933 mhz processors with 1GB memory on my computer and it
runs very quickly and smoothly, nearly as well as a single processor
machine that's twice as fast.

Stew Rorer