When the company launches Windows 7 on Oct. 22, it will price Windows 7 Home Premium, likely the most popular of the three editions available at retail, at €119.99 in the European Union (EU) and charge £79.99 in the U.K., an EU member that has retained its own currency. Those prices are the equivalent to $168.66 and $132.14 U.S., respectively, at Saturday's exchange rates.

U.S. consumers will pay only $119 for the same software after a two-week pre-order sales discount expires July 11. That means EU residents will pay 41% more, and U.K. consumers 10% more, than U.S. buyers for Home Premium Upgrade.

Other editions will come with an even higher surcharge. Windows 7 Professional, the key retail edition for businesses, will sport a price tag of €285, or $400.60, and £189.99, or $313.84, at Saturday's exchange rate. In other words, EU customers will pay twice the $199.99 U.S. price; U.K. buyers will pay 57% more.

The top-end Windows 7 Ultimate, priced at $219.99 in the U.S., will cost €299 ($420.27), or 91% more, in the EU, and £229.99 ($330.36), or 50% more, in the U.K.

Some of the money Microsoft stands to make on the European editions of Windows 7 comes from the weak dollar. Last week, for instance, the dollar fell against the euro the , hitting $1.41 per euro.