I added one computer to my setup,
performance went from [avoid cities at all costs] to [try to avoid the centre of the city in peak hours]

Current setup:
Main computer: P4 3.0Ghz 1Gb Ram
20" CRT + 19" TFT in 2560x1024
Runs 3 x WoW
keyclone maxbkfps 10 maxfps 30

Secondary puter: P4 2.4 768Mb Ram
2x 15" TFT in 2048x768
Runs 2 x WoW
keyclone maxbkfps 10 maxfps 15

I only loose a slave in a city once in a while on the main computer.

Keeping old hardware around the house is great for these kind of projects
I still got 2 x 15" lying in a corner doing nothing and we're about to replace the 2.4 systems at work,
so I'll probably add another "Secondary puter" and have my main computer just for my main and anything else I want to run it.