using an old Quicken but upgrading as well

[GNV]

If I have a full system backup with Snow Leopard on an external drive, can I boot from it and use Quicken there, then boot from an upgraded computer for the rest of my activities, thus getting around the fact that my Quicken is 2004 and works with Snow Leopard?  I haven't upgraded because of that.

[GNV]

Well, I think I can do it;  now to partition that external drive so that I can keep an old system separate and back up the new one.  Computers are time-sinks.