> You just need millions of computers, millions of petabytes

What if you build it like a distributed network focusing on anonymity / less centralization / less advertisement. Of course, it will be a completely different business then google, but this kind of search competition could quickly destroy google business.

Of course, crawling, indexing and distributing billions of URL's is not an easy job, I don't say that it can be done by someone over the weekend, but you don't have to be Microsoft at all to be able to do it.

Big companies like Google has a big inertia. Google built a complete industry (the advertising) over their centralized search system, which is very hard to be changed. This is why they are very vulnerable.