...

...

India ranks second in the regionwide listing for searching 'linux' in google, US isn't even on the list.

http://www.google.com/trends?q=windows&ctab=0&date=all&geo=all

India tops this one.

And finally, we have:

http://www.google.com/trends?q=linux%2Cwindows&ctab=1&date=all&g...

Also, from the "About" page:

1. How does Google Trends work?

Google Trends analyzes a portion of Google web searches to compute how many searches have been done for the terms you enter relative to the total number of searches done on Google over time. We then show you a graph with the results -- our search-volume graph. *snip*

6. How accurate and up-to-date is the information provided by Google Trends?

Google Trends is a Google Labs product, which means that it's still in an early stage of development. The data Google Trends produces may contain inaccuracies for a number of reasons, including data-sampling issues and a variety of approximations that Trends makes use of. We hope you find this service interesting and entertaining, but you probably don't want to write your PhD dissertation based on this information. We'll aim to update the information provided by Google Trends monthly.

So its a "portion of the web searches" and its still very much under development. I'd take this with a grain of salt.

Regards, Siddhesh