Researched and purchased several new machines for the lab. We didn't go with the "Technology Solutions Centre" as it is by no means clear whether I can jack up the RAM, dump Windows, and still have a cheap, quiet, warranted box. As it was I got fabulous machines that are dead quiet and quite powerful for a within-budget price.
So, for anyone listening, the question is (for next time):
If we buy a machine on offer, can we double the RAM, drop Windows (and actually save on the price) AND keep the warranty as-is? I'm concerned that buying it with Windows is part of what makes it cheap, and that the warranty is dependent on running Windows.
If we get the right answer maybe next time we'll buy our boxen through TSC.