A major plank of Microsoft's corporate strategy has always been to buy products from its competitors, rather than pour resources into home-grown developments. Famously, back in 1980, when IBM was seeking an operating system for its PCs, Microsoft bought q-DOS (a.k.a 'Quick and Dirty Operating System') from developer Tim Paterson for $50,000 and called it MS-DOS. As we all know, MS-DOS licenses subsequently earned Microsoft billions.
With the purchase of anti-spyware specialist Giant in December 2004, Microsoft obtained the basis for its AntiSpyware product, which has now appeared in beta form. There are plenty of other anti-spyware programs available: the most popular, Ad-Aware, is available in a free version, although others are paid-for products. Life could become more difficult for the latter if the final version of Microsoft's tool becomes available for free.