No. Imagine I'm a 4-person startup hoping to capitalize on my revolutionary new psychoacoustic library. Copyright protections don't prevent Microsoft from reading my library, learning how they work, and creating a clean-room reimplementation. Similarly, it's hard to create a trade secret out of something that will need to run on every customer's machine.
Will patents help you against Microsoft? Does your four person startup really have the resources to take on a major legal team? From the patents question in the interview at http://www.nature.com/news/2010/101007/full/news.2010.525.ht..., it sounds like defending a patent isn't a pretty or an affordable business.
Patents take 5-7 years to issue and cost hundreds of thousands of dollars to litigate. They're more like claymores rigged to a dead man's switch than they are a real defense.
But that's orthogonal to the question that was just asked.
However, if that idea is worth selling, you will be ahead in the market. Microsoft will need to catch up. They may buy you out. Software typically goes obsolete for reasons other than the "need" for protection.
Besides, by the time Microsoft does that, some other algorithm could quite possibly be created by somebody else.