I know it's not really much help to you, but I've used two different printCD versions... firstly the one that came with my old Epson R300, and when that gave up the ghost, I got my current Epson R360, and I've just loaded PrintCD to see I have version 1.5E.
Never had a single problem running either, on my Vista x64 system.
As I said, I know this doesn't really help you, but just thought I'd mention it, as there obviously is a way to get them running.
I also don't recall doing anything special to get them going, just installed from the CD, and off I went.
Have you tried the obvious, like running the installer as administrator, and/or running the program after install as admin?
Vin.