I can't install qvpdf correctly on a 64-bit Win 7-Version.
It refuses to find a sutiing ghostscrip-dll. It does not want the 64-bit Version and I also tried a 32-bit version which did noch work.
Same happening to me.
I have successfully installed qvPDF on win7 64 bit.
install ghostscript 32 bit from http://pages.cs.wisc.edu/~ghost/doc/GPL/gpl902.htm
then in qvPDF configuration, double click on the red cross next to Ghostscript DLL in System Check.
It will ask you to browse and select the gsdll32.dll. Brows to C:\Program Files (x86)\gs\gs9.02\bin\ and choose the DLL and then click copy.
That should do the trick.
Hope that helps someone out there.
From my experience it seems that qvPDF has a couple of problems with x64 systems. Both of these relate to the incompatibility of the included printer drivers with the aforesaid x64 systems. The HP Laserjet 4550ps driver was never designed with x64 technology in mind and has never been updated to compatibility. It would seem to also be the case for the qvPDF printer to be the same, which says something about the author/s of the qvPDF software. It being almost too obvious to mention here; that I'll refrain from doing so. I don't know that this will suffice, however it may be helpful to note.