microsoft

They create upgrades for many reaons. The main reason is that they find any weakness in thier product that was not discovered when it was first created and tested. Another reason is that new viruses, spywares are created by hackers, etc and to prevent thier products from these, they create a patch for thier product. Although anti-virus program may protect applications from virus, etc, microsoft want thier products to have self-protection ability, too.