I've been thinking of providing at least four computers to each student for my Exchange class. However, the thought of all the cables, KVM switches, the CPU fans, KVM switches, etc., -- not to mention the cost -- made it an impractical solution.
Virtual Machine technology provides the best solution for simulating a real-world environment in class, home labs or even at work for test labs. Microsoft has created a great course for Exchange 2003 using its recently acquired Connectix VirtualPC. The big drawback is it's a RAM hog (compared to VMWare), amongst other things.
VMWare manages memory more efficiently, has better support for non-MS OSes, allows you to do more complicated things like clustering. Either way, it is better to load up one computer with a fast processor (with hyperthreading) and as much RAM as one can fit into a system (ideally 2? 4Gb) to simulate a network environment.
This was first published in February 2004