Gerry, check the license agreement. Maybe it allows you to download the appl to different OS's without additional charge. You might have to transfer the license from one installation to the other, but it sounds like you're okay with that. If not, it's what, 10 bucks? Just shell out twice for a great program. Wouldn't you have paid $20 the first time?
.......... Tom Lane
Ignorance is only stupidity when it's a chosen state.