The discounted preorder Windows 7 upgrade versions of Home Premium and Professional editions are apparently selling out quickly in Europe, especially in UK, Germany and France.

On July 11, a similar pre-order offer ended in the US, and the supply there appeared to be more than plenty!

Though the Europe deal, with considerably reduced prices, is supposed to last till August 14, Microsoft has made it quite clear that the phrase "while supplies last" better determines the duration of the offer. However, the company refrained from disclosing the number of copies on sale at the discounted rates.

Going by the reports pertaining to the sale of the preorder Windows 7 upgrade versions, there has been a complete sellout at some Amazon sites and at spots in Germany. In addition, the software giant's European online store too was overwhelmed by demand is indicated by the fact that most buyers came across an error message.

Microsoft said in the English-language posting: "Due to the eagerly anticipated Windows 7 pre-order offer we're experiencing a higher level of demand on our website than usual. This means you can't access the site right now and we're sorry about that. We'll be back up and running as soon as we can so please try again soon to get your hands on a copy of Windows 7!"