Linux is not suitable for desktop use unless you have a) a very serious understanding of Unix in general and Linux in particular, b) old hardware (10+ years) to make pretty sure it will all work with Linux, AND c) no requirements to run modern highend software like most games, photoshop, etc. etc.
You don't need old hardware and you don't need a serious understanding of Unix in general or Linux in particular. But you do need (c) -- if you need a _particular_ application that does not run on Linux, then obviously Linux is not for you.
I'm running linux on an AMD64 machine. Dont think thats 10 year old hardware, probably should check that :)
I'd recommend Fedora or Mandrake if you are new to Linux. Mandrake is known for its vast hardware drivers, and Fedora was pretty easy when i started to learn linux. I'm currently running Gentoo on that AMD64 machine and Fedora Core 4 on my laptop. Who needs Photoshop when you have gimp?
I work daily with Fedora Core 3, and am tempted to switch to SuSE to learn more about that desktop and work with it. I have not had a problem with Fedora / RedHat, and admit that I have not explored GenToo, Mandrake, etc.
I tried Debian, and quickly lost interest with the mammoth install issues. I also want the ability to install from local FTP sites... and Fedora / RedHat allowed me to do that.
I have not had a desktop issue yet... GIMP worked fine for me for photo edits, Evolution for email, kPalm works with the Palm, etc. I am not a gamer, although I have a few of them on my Mac for when time slows down a bit, and I like to get inspired.
You do not need a 10 year old computer as JWenting suggests. You can do linux today, and have a quite pleasent experience. Just be sure to think about backups, and how you are going to manage things if your hard drive goes bad. Linux supports burning of CD-ROMS, DVD's, and even the thumb drives.
Redhat WorkStation (RHWS) free 30day trial when registering an account at redhat.com
includes updates. cake install.. download the ISOs and burn to cd. ensure you can
READ them on an old CDrom drive first.
For desktop Linux, I would recommend Ubuntu. I use it as my primary operating system, and all my hardware worked first time, without me having to configure anything. For example, ATI drivers usually are a real challenge to install on most distros. With Ubuntu, you simply the 'xorg-driver-fglrx' and the 'linux-restricted-modules-386' packages, change 1 line in a config file, and it works.
In regard to applications, there are apps for most tasks. Gaim and Xchat for chatting with IRC, MSN, Yahoo, AOL, etc; OpenOffice.org for office tasks; Evolution/Thunderbird for email; Firefox for web browsing. There are also lots of games available in the package manager. You could also purchase Cedega, which allows you to run Windows games on Linux.
I also tried Kubuntu, and it is good. But I prefer Ubuntu, because I don't like the KDE Desktop that much. IMO it is too bloated. Because Kubuntu and Ubuntu share the same package repository, if you install Ubuntu, you could also install KDE later from the package manager.