1. It's totally 100% FREE! No software cost, no licensing cost, no update costs...
2. It can run almost any computer architecture
3. Most Linux distributions are supported by communities of thousands of IT and programming experts and very knowledgeable end-users (oh yeah, community support is also 100% free!)
Here are my top choices of Linux distributions:
Ubuntu: a free, Debian derived Linux-based operating system, available with both community and professional support. With the release of 8.04 (Hardy Heron), Ubuntu may very well be the most user-friendly and flexible Linux distribution available today.
Ubuntu Home Page | Ubuntu
Ubuntu is and always will be free of charge. You do not pay any licensing fees. You can download, use and share Ubuntu with your friends, family, school or business for absolutely nothing.
Fedora: a Linux-based operating system that provides users with access to the latest free and Open Source software, in a stable, secure and easy to manage form. Fedora is backed by the industry leader in Linux products, Red Hat, and based on Red Hat Enterprise Linux.
Fedora Project
Note: Red Hat also backs the JBoss Enterprise Application Platform. JBoss is the Open Source, J2EE application server that Practice Director is based on.
Fedora is all about freedom and rapid innovation.
OpenSUSE: a community project, sponsored by Novell and AMD, to develop and maintain a general purpose Linux distribution based on Slackware. With backing from some of the biggest companies in the IT industry, openSUSE has become a user-friendly and widely used distro.
openSUSE.org
The openSUSE project is a worldwide community program sponsored by Novell that promotes the use of Linux everywhere.