Linux and Viruses
http://www.whylinuxisbetter.net/items/viruses/index.php?lang=
Linux and Security
http://www.whylinuxisbetter.net/items/security/index.php?lang=
Having read the information above this does not mean Linux is immune
http://www.linux.com/learn/tutorials/284124-myth-busting-is-linux-immune-to-viruses
Use the Web reponsibly and nothing should present a threat. I have been running Linux since 2006 with just the Firewall on my router with no problems
Overall a Linux based platform can perform most of the tasks equally as well as a proprietary platform using the likes of Ubuntu and its derivative distros. However Linux does have its limitations with some applications and in particular gaming. For example I retain a dedicated Windows partition to run specific applications such as Office 2010 etc.
I thoroughly recommend Linux Mint 9 LTS which is built upon Ubuntu 10.04 LTS its easy to install and easy to use plus it comes with much of the software you are likely to need preinstalled
Linux Mint 9 LTS Download
http://www.linuxmint.com/edition.php?id=52
How To Dual Boot Linux Mint and Windows 7
http://www.linuxbsdos.com/2010/12/08/how-to-dual-boot-linux-mint-10-and-windows-7/
Linux Mint 9 LTS Release Notes/User Guide
http://www.linuxmint.com/rel_isadora.php
You download the ISO. image of Linux Mint 9 LTS then you need to create a Bootable LiveCD for installation
https://help.ubuntu.com/community/BurningIsoHowto
Linux Mint 9 LTS can also be run straight from the LiveCD from Boot without touching your Hard Drive
Once installed I recommend updating to Firefox 5 as Firefox 3.6 comes as default with Linux Mint 9 LTS
How To install Firefox 5 on Linux Mint 9 LTS using the Firefox Stable PPA
http://www.webupd8.org/2011/06/firefox-5-lands-in-firefox-stable-ppa.html
LUg.