Hi MsMonty,
I have books by both Dr. Vliet and Dr. Gillespie and both are very anti-PremPro, Premarin, PremPhase, etc., because they are conjugated estrogens unnatural to the human body (however, they are not against HRT, as both of them use it). There are so many bio-identical options, particularly patches like Vivelle Dot, Activella and the rest. If I were you, I'd read the interviews with these doctors (and others) right here in Power-Surge. They are very enlightening.
Also, did you try any natural alternatives first, like soy, herbs, etc.? Just a thought.
Hope you find something you'll be more comfortable with.