G'evening Philal,

you can use 1 or more computers... you are only limited by your hardware and how many wows it can run at one time.

personally, i started out using a desktop and 2 laptops to run 5 wows. currently, i run all 5 on just my desktop... which is pretty low end by today's standards

my specs:
cpu - amd athlon 64 3500+ 2.2GHz single core
mem - 3070MB
video - NVIDIA GeForce 8800 GT OC w/ 512M
displays - 21" samsung @ 1280x1024 and 22" acer @ 1280x1024 (horizontal span)
performance - 5/25 fps

if you have any questions, please feel free to drop me a note