Actually, the Rival Ball demo can play your DX-Ball 2 board packs. If you start the Rival Ball demo and click the 'Standard Game' button, you'll end up at the 'Select Board-Set' screen, and in the top-left-hand corner there's a button you can click to select your DX-Ball 2 board pack.
Incidentally, you can also play DX-Ball 2 in a window. Just hit F7 on the main menu.