Quote Originally Posted by yuki
I'll soon start to lvlup 2 Warlocks with a iMac Core 2 Duo 2Ghz with 2GB Ram (I can run 5-6 instances). To run several WoW instances, just copy and paste the "World of warcraft" Application (Not the folder) You'll win some Hard Disk Space, then run each WoW Application (World of warcraft, World of warcraft 2, Etc) And Log in.
You can also install Clonekeys http://code.google.com/p/clonekeys/
You'll have to add each WoW Window to the list (With the "+" Button). And now, each key you use on your keyboard will be bind to the other windows.
Yuki

And... Good luck!
thats exactly what i did! it works well too, i have same specs as him xept only 1GB RAM so i get 3 running, 4 if i really dont care about quality