PWM should work with future Windows systems. If it doesn't, then chances are, PWM is the least of your concerns actually.
The on-line edition could be the most feature complete version out right now that is not dependent on browser type. Only requirement is JavaScript basically. Not many browsers with JavaScript now would not have the needed amount of support to run it actually. For no browser what so ever, there's the desktop edition, command-line edition, and Yahoo Widgets edition. (There's a Mac version too, but I'm assuming you're not running a Mac because of your Windows comment)