Detailed System Requirements

'Long', detailed/specific, System Requirements like this http://www.fogcreek.com/FogBugz/docs/60/topics/setup/UnixSystemRequireme... is what usually calls for a Virtual Machine, specially for such a small load. Fog Creek could very easily have a virtual machine ready for their clients in case they don't want to go through the trouble of figuring all that, and worse: find that they cannot activate (or don't want) one of those.