Linux Operating System

While it can depend on several factors and is certainly not set in stone, Linux is often an ideal choice for an operating system. Obviously, certain business applications will dictate the use of Windows, just as others would make MAC OS the preferred solution. Personally, I have used Linux on my desktop exclusively for over five years and for several years prior to that I had a dual-boot setup and used Linux for server and firewall functions. Since I do encounter an occasional need to use Windows, I have a laptop that is setup to dual boot XP and Linux.
Considering Microsoft Vista? Scroll down and check out some of the links provided regarding Vista first. Currently, I would recommend XP over Vista if you must choose the lesser of the two evils. However, Ubuntu with Beryl is a much better solution in many cases and is usually considered "prettier" than Vista. Support continues to grow for running Windows programs in Linux with WINE, Cedega and other traditional emulator solutions. The primary advantage to running windows programs in WINE is that a windows system or user program crash very rarely, if ever, affects the Linux system or requires a reboot. See the Emulators page for links.
For more info on Vista v Ubuntu/Beryl, here is a review from InformationWeek, a followup on deficiencies of the InformationWeek article by the Ubuntu folks, and a video. Another quick review can be found here.

Why Linux?

Stability
Security
Speed or Effective use of Hardware
Cost
Open Source

Cost Benefits of Open Source Software.
Should your business use Linux? - an editorial by Andrew Grygus, Automation Access
Five reasons NOT to use Linux - by Steven J. Vaughan-Nichols

Top 10 Ways to Protect Your Linux Home System

For a rather unbiased comparison of Windows and Linux see this Wikipedia Article.

The choice of which Linux distribution to use can be a daunting one. There are dozens to choose from and while they are all basically the same, there are several differences amongst the distro's which can matter depending on what the intended use of the system is. The most visible differences generally are in "user-friendliness". Generally something desired for a desktop machine or for a server that will be administered by those not so comfortable with a command line and text interface. Though to someone like myself the user-friendly differences mean very little personally. Throw me in front a machine with just about any distro on it and I could very likely do just about anything that could be done on any other as far as basic functionality. Doing something like installing a Ubuntu package on Slackware may be an issue, but I could probably find the same source software that is in the Ubuntu package and just compile and install it. What may be important is stability and granularity of the system. In such a case, the latest and most user-friendly distro may not be suitable. Listed below are a couple basic recommendations, but if you would like a personalized one based specifically on your situation feel free to contact me.

Recommended Distributions

DistroWatch compiles the latest and most comprehensive data on available Linux distributions. Their top distributions list can be found here.

Slackware - Slackware is one of the oldest distributions still active and remains one of the most stable released distros. It is not uncommon to see uptimes exceeding one year. For general use, particularly where stability or long uptime is desired, or for older hardware Slackware is a very good choice.
"Since its first release in April of 1993, the Slackware Linux Project has aimed at producing the most "UNIX-like" Linux distribution out there. Slackware complies with the published Linux standards, such as the Linux File System Standard. We have always considered simplicity and stability paramount, and as a result Slackware has become one of the most popular, stable, and friendly distributions available."
PuppyLinux - "Puppy Linux, started by Barry Kauler, is a small (28-72M), fully featured Linux distribution.
Mission Statement
- Puppy will easily install to USB, Zip or hard drive media.
- Booting from CD, Puppy will load totally into RAM so that the CD drive is then free for other purposes.
- Booting from CD, Puppy can save everything back to the CD, no need for a hard drive.
- Booting from USB, Puppy will greatly minimise writes, to extend the life of Flash devices indefinitely.
- Puppy will be extremely friendly for Linux newbies.
- Puppy will boot up and run extraordinarily fast.
- Puppy will have all the applications needed for daily use.
- Puppy will just work, no hassles.
- Puppy will breathe new life into old PCs"
EnGarde Linux - EnGarde is my personal choice for internet connected servers. "The Community Edition of EnGarde Secure Linux was designed to support features suitable for individuals, students, security enthusiasts, and those wishing to evaluate the level of security and ease of management available in Guardian Digital enterprise products. Its development is very much driven by not only the requests from the community, but also their continued participation."
IPCop - IPCop is my recommendation for firewalls. "IPCop Firewall is a Linux firewall distribution geared towards home and SOHO (Small Office/Home Office) users. The IPCop interface is very user-friendly and task-based. IPCop offers the critical functionality of an expensive network appliance using stock, or even obsolete, hardware and OpenSource Software."
Ubuntu is recommended for those new to Linux. Also check out the audio, video, or graphics page for Ubuntu Studio, a multimedia specific distribution of Ubuntu.
"Ubuntu is a free, open source Linux-based operating system that starts with the breadth of Debian and adds regular releases (every six months), a clear focus on the user and usability (it should "Just Work", TM) and a commitment to security updates with 18 months of support for every release (and with 6.06 LTS you get 3 years on the desktop and 5 on the server!). Ubuntu ships with the latest GNOME release as well as a selection of server and desktop software that makes for a comfortable desktop experience off a single installation CD."

General installation information and specifics on some Linux Distributions can be found here.
If you are interested in selecting a linux distribution check here for the top ten Distro's and more.
Ubuntu unofficial Starter Guide contains a ton of installation info for Ubuntu.

Considering Vista?

Protect your freedom!
Why Vista's DRM is Bad For You.
Dim Vista
Why Vista is defective by design
Independent Research Confirms Allegations That Vista?s Anti-Spyware Protection Has Holes
What's wrong with Microsoft Windows Vista?
If you have Windows XP, why do you use linux? - a discussion on the Ubuntu
Windows v Linux security: the real facts forums.
Much more can be found here