xynthetik,
Horndude and Greg are Correct (again) It's not all Command line but when installing programs this is usually Done from Command line. another Go is the Nvidia if you are using this HW you are fine, I mearly put it in my above post as I was not sure what HW you were using but please still make suree it is compatible you can do this by checking the Manafacturers site to see if Linux support is Availible
but Horndude is right About Knoppix being a pain in regards to a full install as a live CD it works great (Saved me on countless Occasions) so you'd be better off using Another Distro, As for IM programs you can omport your IM contacts from Windows MSN into a IM program for Linux such as gaim or Kopete.
Now for your Distro Question... When asking Linux users your answers will differ greatly every Linux user has their Preference, Horndudes advice is the Best test a couple and pick which one you like.
My preference is PCLinuxOS, Everything works Right from the box, Easy to install and works well as a live CD that you can then install from
http://www.pclinuxos.com/news.php
If your looking for somthing a little more Advanced I reccomend Slackware (to learn Linux)
http://www.slackware.com/
but Please Checkout Tux Mobil (link in post above) it has all the H/W info for which HW Periferals are supported in Linux and What Distro works well on which laptop
Somthing else you might want to check out is this Link
http://www.zegeniestudios.net/ldc/
It is a Linux Distro Chooser it askes you a series of Questions then based on that info comes up with a Linux distro Suited to you
Also Please note that if you are dual booting (Windows and Linux on the Same Machine) buy another HDD to install Linux on it saves alot of hassle in the long run, Although you can partition and install a dual boot system with one HDD if anyuthing goes wrong it can get messy
Hope this Helps,
Jake