Adobe Acrobat Reader 8.0

[Graeme Forbes]

Dov wrote:

"The problems that I mention are more prevalent under Windows
than on Mac"

which sounds about right. But although

"even the Mac has issues with such parallel
installations. Some program must respond to double clicks
to open/process files from the user interface"

you can easily set a default. I run Acro5, full version, and Acro7 
Pro (default), on the same machines, but the solution to having them 
cohabit peacefully may be that Acro5 is set to open as a classic 
application.

Graeme Forbes