I have just built a new i7/Asus computer, at first tried working with xp pro, then decided on a dual boot with Win 7, 64-bit, just to see if it was time to move in the 64-bit direction. It was, I believe, time. I like it so far, mainly because it seems much faster, not too wild about all the mac-like flashy-pop-uppy interface, but i'm sure that can be tamed as i learn more about the OS. However, I initially had some issues with the z3100 printer driver, and from info I found on this forum, I installed the Vista 64-bit drivers. Frustration at first, but after a reboot of the printer, I was able to synchronize paper presets, get a print preview window and print out of PSCS4. I haven't had it running long enough to put it through all the paces, but so far, I like it and I think it's going to work fine.
One note....I had to install most of the HP ICC paper profiles manually..find them in the HPDesignJet folder in Program Files, right-click on Install. This will put them in the Windows color profiles folder and you should be able to find them with any program after that.
I might add that I have yet to try to profile a paper from the computer, but that is always possible through the printer's control panel, if I am not mistaken. Then use the HP printer utility to sync papers.
Hope this helps!
Ed, the ridge runner