ok, just got off the phone with Electric Quilt (they are just 'up the street' in Bowling Green, Ohio).
she said that yes, EQ5 will work with Vista (and with the Service Pack 1). When you install, you need to select 'installation 2' (you have two choices when you install and for Vista OS you choose the second one).
should be interesting! here I go, off to order it!
Thanks all of you enablers!