I don't think it's an OS issue - Painter had the same problem, in windows 9x as well as the NT versions. EricofSD is running it in both OSes, so unless there was an installation problem (and it sounds as if Jim Burton has it on his system, just not running) it should be more-or-less XP friendly. It may be MC used a signed integer to report memory availibility - the SimCity 2000 installer told me I had -16MB free on my 32MB machine, and should free more RAM if I wanted it to run (fortunately the game itself was fine).