Why did you give up on XP-64 previously, and after giving up, what did you change to? I found XP-64 very good when i was using it. very stable, and fast. If your problem was hardware drivers though, then Vista-64 is going to have the same problem.
From experience, Vista-64 and ArchiCAD 12 like each other very much, especially on a Quad-core. My rig(details in my signature) generates sections in ArchiCAD 12 in just over half the time it takes a Duo-2.8 to do the same thing. It's also about 10 or 15% faster than XP-64 was before I upgraded to Vista.
I would even go so far as to say that Vista-64 is the fastest Operating System to run ArchiCAD 12 on right now. Although I will probably get burned alive for saying so.
Josh Osborne - Central Innovation
HP Zbook Studio G4 - Windows 10 Pro, Intel i7 7820HQ, 32Gb RAM, Quadro M1200