Hello,
First, let me congradulate you on daring to leave Windows. One thing to bear in mind: Linux is different, but not so different. Think of upgrading from a car to a Truck.
There are a variety of Linux flavors out there. I work a lot with Red Hat Linux, although RH changed their business model, and the family is now called Fedora. People have mentioned that Fedora is not quite ready to go, and yes, there are rumblings of anger against Red Hat for dropping of the map. Fedora should be ready to go soon, and have all wheels rolling. I find RedHat to be the easiest to work with, and I am able to do a lot of programming / networking / filesharing with it.
If you have Macintosh hardware, the Yellow Dog Linux ( www.yellowdoglinux.com ) is a "RedHat for Mac". Go check it out -- it works well for me too!
I tried Debian to see how well it would work, and was deeply disappointed with it. I had to install from CD's, instead of my preferred FTP method I use under RedHat (able to setup many machines at once over FTP, and no disks to flip or replace). Debian also would not get things right with my Laptop, such as proper screen depth and size. I was disgusted enough to just throw the disks out.
I do not know much about Mandrake or Slackware. Other friends here can offer an opinion.
I am intrigued by FreeBSD, and while it is not a Linux (it is a UNIX), if I get some hardware freed up, I think I will explore that OS.
There are tools for the internet (Mozilla), Office-type work (Open Office), Instant Messaging (Yahoo so far!), Tunes (XMMS), Burning CD's and so forth. Even Palm stuff for Syncing. The only lacking tools that I see are Quicktime/Windoze Media Player abilities, and a disk optimizer for clearing fragmentation.
Enjoy your quest for the best OS. Let us know how it went.
Christian