It is pretty messed up if the Brits are paying twice the price in US Dollars. Unless, Microsoft's operations in the UK _cost_ twice as much. For example: If I go to the Shamrock in Gainesville, Fl and buy a pint of Guiness Draught: that's gonna cost me about $3.50, in a town where minimum wage is $6/hour. If you have to pay 3.50 uk pounds for the same pint, and your minimum wage is about 6 pounds/hour -- then the cost difference is 200% in trade and nothing domestically.
The difference in the product's trade cost is your economy's fault. There's all these curves and charts in economics to explain currency and "real value" (read "ILM curve"). All in all, if they are earning the same profit rate for their UK products -- then it's Britain's fault that the product costs twice as much in dollars. It would seem that everyone there wants to get paid twice as much in dollars (ie. 2:1 currency ratio). It's generally not a good thing to have an expensive currency unless you're a self-sufficient nation; not a crowded island. That's why the US worked so hard through the 80's and 90's to bring the value of the dollar DOWN. The result makes it easier to _sell_ US products and reduces the benefit of overseas production.
At the same time, that's why China has artificially locked it's currency at nearly 8:1 under the dollar and euro (prolly should be 2.5-3.5:1 on the dollar) -- to suck money in on trade. It's great except when they have to buy something foreign. Case in point: Vista Ultimate is about 2000-2600 Yuan here ($300-400). At the same time, 650ml bottle of cold beer costs 2.50 Yuan, loaf of bread 3-5 Yuan, and the average wage is ~700 Yuan per month in the cities. So, it's not really the Brits that are getting the shaft.
Rob