Virtualization

VM's usually come into need with Windows environments ... because MS wants you to use a zillion servers to do what other OSen suffice with two. I've been told that I can't achieve real DR capabilities if I don't have *three* DC's running! Then comes SQL Clustering ... add two machines ... IIS needs to be in another one ... blah blah ... and some clusterized apps don't play well with non-clusterized apps. So the need to virtualize becomes critical.

Other stuff I've seen is the development servers problem. It is much easier to just buy one Blade with tons of RAM, hook it up to the SAN and give it gobs o' storage. Then you set up as many dev servers as you want, thus freeing up your budget for the actual production servers, while meeting dev and QA server needs.

I do agree, however, that instead of a zillion "desktop PC" VMs, you could just solve that with a much cheaper solution involving a Win2003/2008 Server with a zillion Terminal Services CALs ... which might be even cheaper than going the VM way. Especially when you can just slap Linux on the PCs and make 'em run rdesktop at boot time. Whoopee!!