I was reading a very useful book, that is Linux Starter Pack.
Their introduction is:
“New to the wonderful world of Linux? Looking for an easy way to get started? Download our complete 130-page guide and get to grips with the OS in hours rather than weeks or months. We show you how to install Linux onto your PC, navigate around the desktop, master the most popular Linux programs and fix any problems that may arise.”
Great! Quite interesting, right? So as the book is.
Those who are planning for a migration and those who migrated and are still newbies can find it very useful. Following points gives clear answer for “Why should I use Linux OS?”
1. Linux is free! No legal issues!
2. Linux looks and works a lot like Windows, much better 
3. Linux has lots of software ready for you to try, that too free of cost.
4. Linux is secure by default. High security for your PC.
5. Linux is smart by default. Says about great performance.
6. Linux looks great, visually and in all sense.
Download the PDF Version for the book.
Also if you are choosing Ubuntu, from a myriad of Linux Distros, as I am using that , you may find this pocket reference as very useful again. It contains all the howto(s) with Ubuntu.
Downloading it here. Ubuntu Pocket Reference.
Do not agree with the 2nd point. Windows and MAC is thee best when it comes to UI and User Experience. Linux is far far behind. Linux is best as a server product and security. But for a novice, to understand linux, he simply has to be a genius.
I agree to that. Few days back I read that Vista has the best Visual Experience. Also they said Vista has a poor rating when it comes to performance. With Mac I agree.
Linux delivers good User experience + good performance with less memory.
When you say Linux delivers good user experience, I assume you are referring to developers and users and not the non-technical crowd of users.
Yes Tom, I am referring techies..