Bill is the man behind some of the most famous and successful computer products in history including Windows, Word, Internet Explorer and now the XBox.
The success of his company has caused jealousy amongst IT rivals, who believe that Microsoft has used unfair practices to ensure the success of their products.
But on his first trip to the UK for two years, Bill told Sarah that their success was due to "doing low-cost products and constantly improving those products."
If it wasn't for Microsoft, he said, there would be many people who would never have experienced computing.
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