Two totally different scenarios, and although I'm not using Vista Ultimate - I've had no problems with either Home Premium or Business - as far as I know Ultimate is Business with the multimedia extensions of Home Premium, or if you like Ultimate is Home Premium with the networking extensions (domain authentication & security) of Business.
In that other thread, the problem relates specifically to deleting files, not to uploading/dowloading or explorer crashing - and with Windows 7 (64bit), there is a noticeable performance degradation in deleting files as compared to XP (or Vista), but in my case, nowhere near that described by the original poster, and also not a true comparison as the XP system was on gigabit, and the W7 system on 100mbit.