Bjorn,
I've been running PM 4.6.1 on the Windows 7 RC1 Build 7100 for several months now with not a single issue. Application is very robust on this build. I can open contact sheets with over 10,000 images in a matter of 10 seconds or less. Image files open very quickly in CaptureNX2 external editor. I'm running an AMD PhenomX4 quad-core processor with 6GB RAM.