Why choose Linux as the platform for your cluster? Below are the representation of web pages in Google for "computer cluster + OS" and for "tutorial + OS" for different operating systems. In the blue bar, the representation of other common, and less common, subjects are shown. In the tutorial graph, the language term shows the representation of "tutorial + LANGUAGE". All page numbers in units of 1000.

There is about as many pages about Linux clustering as about Phil Collins. Interestingly, there is more written about Kenny G than Windows clustering. You decide.

There are as many Linux tutorials as tutorials on English. Potentially, finding how to cluster on Windows is equivalent to finding documentation on how to speak Russian. If you want to cluster with PalmOS, you're more likely to find documentation on Bulgarian.