The SD version for XP/2000 doesn't support X/Y axis mouse yet but a new version is due out soon as I understand it.
Frankly, I don't why they just can't support a joystick.. it's not like it's alot of work, quite the opposite. While using mouse flight, it's functioning just like a stick.. minus the comfort, minus 20 buttons and minus the familiarity. It's great they have designed an alternative to folks buying a $60-100 stick but hey.