>The difference is in how many users are on XP (50%?) vs. older than OS X Leopard (low single digits). And the reason for that is probably that Microsoft keeps

>The difference is in how many users are on XP (50%?) vs. older than OS X Leopard (low single digits). And the reason for that is probably that Microsoft keeps so much backwards compatibility that the cost of not upgrading the OS is much lower than on OSX.