I use PD7 on Vista 64 bit.
I believe that it is working not too bad although I am having a couple of issues.
1. I've been having problems with PD and chapters. It seems that when I go to the Create Disk stage, if I have more than one page of chapters then the DVD will not run properly when playing back on our DVD/TV. If I stick to only one page of chapters, then it works ok.
2. I'm having Backup BIOS CHKSUM ERROR problems with my PC but most likely this is a separate problem from PD7.
John