Some advice from a Linux newbie:
I just installed Linux on a desktop computer of mine about 2 months ago knowing about as much about Linux as you do (i.e practically nothing) - no exaggeration. With Ubuntu Linux you can get away with this. When I bought a wireless card to put into my desktop, Ubuntu automatically detected it and configured it when I restarted my computer (D-Link WDA 1320 PCI wireless card). I tried some other Linux distributions, but many of them required too much technical know how for me to setup.
Linux also seems to have been way ahead of Microsoft. 64-bit computing? Linux is the only way to go (we will see what Windows Vista has to offer). The fancy 3 dimensional desktop you saw in Windows Vista previews - its been available for Linux for a while.
Other programs are easy to install - you simply select the Synaptic Package Manager program from the system menu on the toolbar, and you will find thousands of free software programs (let me repeat - free) that you can install. You simply tell Synaptic you want them installed, and it will download and install everything for you. In this respect, I think that Ubuntu Linux is just as easy as Windows, because all of this can be done without any Linux knowledge. These procedures can also be done from command line if you know exactly the name of the package that you want to install.
Linux, however, does have limitations - gaming seems to be the one that most home users complain about. Also, I am of the opinion that there is no better office package than MS Office. If you only use excel for making pretty tables and Word for simple word processing this will probably not make much of a difference to you.
Open Office seems to be the best office package for Linux available currently, and it can do a lot, but you will have to learn to use it, and performance tests that I have seen show MS Office handling complex tasks far faster than Open Office. Additionally if you write any academic or scientific papers and like to use Endnote for bibliography management, you will not be able to do this with Linux.
There are supposedly ways to get all of these windows programs to run in Linux using wine or winex, and I may for the first time today try to install Steam and Half Life on my Linux Box using wine, but I doubt it will be simple.
To me the biggest strength of Linux is that it is far better for scientific computing than Windows because more software is available for it. That being said Mathsoft (makers of Mathcad and Matlab) does not make software for Linux, but there are good free substitutes (like Maxima, Scilab, Octave, R), and Mathematica (not free) is avaialble for Linux (don't know about Maple). Additionally I have not managed to get Genesis or Neuron to work for Ubuntu yet.
I recommend Ubuntu because it is very easy and requires almost no technical know how, yet its fans include not only new Linux users but also Linux gurus. www.desktoplinux.com has articles reviewing lots of Linux distrubutions if you want to research some other options.