I'm not sure about anything else, but RAM, Processor and OS isn't an issue - I run XP Home SP3, 1.66GHz and 0.99GB ram, and Obsidian's been running pretty well for all I know.
And yeah, 0.99GB ram - Que the questions on how on earth I make music on such a tiny machine.
...Or not. Whichever.
Edit: Maybe it's the graphics card? I couldn't run a Mario fangame on a system with more RAM while I can run it on this machine.