The funny thing about this article is that he essentially never mentions (a) design flaws or (b) perverse economic incentives to sell defective software. IMO these are probably the two biggest reason why MS has such a terrible reputation on security.
If you actually knew what you're talking about, you'd know that MS has a VERY GOOD reputation on security. It used to be awful, but they completely cleaned up their act these past few years and now when you talk to security consultants(IO Active, Leviathan, iSec partners, ...) and ask them who's doing a great job, the first name they pronounce is ... Microsoft
In the security world, your reputation is based on real things: the # of issues your code has, how hard you make it for people to exploit your code, whether your system is secure by default, ... not by the number of times you show up in the news, because that last one is purely driven by your market share, not by the quality of your code.
Take a look at SQL Server, compare its security record to any other database with a decent market share on the market.