I'm also new to Linux and have been learning a lot and still have much much more to learn.
There are many diffrent distros, it's open source, so anyone who wants to, can make their own version.
I'm running Ubuntu Linux on a 450mhz, 256 RAM, it's a little slow, but it works just fine, as far as min requirements, you'd have to check with each distro.
I don't know if MS Office is able to run on Linux, but you can get open source versions of most anything by or for Windows. For example, Open Office is much like Office 2003 only it's free.
The desktops seem to be unlimted, and depends on which desktop enviroument you want, I prefer KDE. Yes, they can look very good.
Linux isn't as easy to use as windows, Best thing is to buy a book on how to use linux, some even come with a Linux CD.
From what I understand, security is very strong.
You can always get a live CD, put it in to a bootable CD drive on your windows machine, and restart you computer, it will run Linux off the CD, in RAM, so you can get a feel for it, and it won't hurt you Windows.
I have been told that MEPIS is a good one for beginers, I plan on trying it, I also plan on getting Kubuntu (Ubuntu with the KDE desktop enviroment).
Good luck, hopefully someone else can answer you questions more directly.
Edited by awg1011, 05 September 2005 - 10:06 PM.