Welcome to Linux and Linux.com, glad to have you here with us. I'm in the habit of making lengthy posts here at the forums, often repeating myself, so here goes:
1. There are many Linux distributions. You'll have to choose one to begin your Linux experience. I always recommend new users to try various distributions to get exposed to the unique features of each. So, start by reading about these distributions here http://www.linux.com/distributions/ and after you've decided on one, read point 2.
2. Linux and Windows can't co-exist in the same partition. You'll have to install Linux in a separate partition. The installation procedure for each distro is well documented and a google search is advised. You can also refer to any number of books for guidance. A good place to start is the official website for the distribution. You'll find links to documentation that might come handy.
3. You can start reading about Linux and getting things done here: http://www.linux.com/base/ldp/howto/ It would be beneficial if you google search for how to doing something that your duties require you to do. For instance, "web server linux" would reveal excellent blog posts, forum threads, tutorial, guides, etc. to get you going.
4. Your system is good enough to run any of Fedora, Ubuntu, Mandriva or OpenSUSE. Each of these distros has a dedicated user base and excellent documentation.
Cheers!
Coauthor of Beginning Fedora: From Novice to Professional published by Apress.
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