Don't forget that in 1994 Microsoft agreed to buy Intuit, at the time clearly recognizing the value of the company--in particular the annual updates that 70%+ of customers bought. It would have been the largest software company acquisition in history at $1.5 bn in stock but fell apart under DoJ scutiny.
Article comparing failure to buy Intuit to the failure to buy Yahoo! http://techland.blogs.fortune.cnn.com/2008/05/13/what-micros...
Overview of Intuit/Microsoft history http://www.theregister.co.uk/1999/01/05/why_microsoft_wanted...