From the Amazon.co.uk software bestsellers list:

#1 Windows Vista Home Premium (Upgrade).
#5 Windows Vista Ultimate (Upgrade).
#10 Windows Vista Home Premium.
#20 Windows Vista Ultimate.

The Amazon.com list is somewhat different:

#3 Windows Vista Ultimate (Upgrade).
#4 Windows Vista Home Premium (Upgrade).
#8 Windows Vista Ultimate.
#12 Windows Vista Home Premium.

Why is Home Premium outselling Ultimate in the UK? Could it be the 88% markup of prices in Europe?