Figure that you’re not really conserving resources, just making management easier. Each user is going to need at least one CPU core, 2 GB RAM, 40GB or better of disk storage. That’s for users who are actually using their PCs, as opposed to execs who log in first thing in the morning and check email every couple of hours. Storage is the biggest potential bottleneck – it’s not just capacity, it’s 200 users simultaneously accessing disk – the SAN interface has to be able to keep up with I/O from a lot of requests at once. That means you’ll need a SAN that can handle lots of simultaneous requests – good queuing, low latency and high speed.