So far, running Win 7 Pro 64 here, I've had only one minor problem. Very miniscule, but a favorite free drive partition manager of mine is Easeus Partition Master, however their free version does not work on 64 bit systems. So, I found Partition Wizard, which is oddly WAY too much like Partition Master that it isn't even funny, so it's like I never changed. Other than that everything has been a dream, but, it did make it easier for me that I installed Win 7 64 on my Dell Laptop, Dell had already developed, or had the respective company develop, the necessary drivers and had them posted a full two weeks prior to the street launch of Win 7.