Here are some fixes for known problem (k)ubuntu packages.
Get w32codecs from:
wget -c http://www.debian-multimedia.org/pool/main/w/w32codecs/w32codecs_20060611-0.0_i386.deb
sudo dpkg -i w32codecs_20060611-0.0_i386.deb
To listen to mp3's etc using amaroK use the xine engine & install libxine-extracodecs. If you are in the the us you will need to use a different mirror as this package seems to have been removed from the us repos. To burn mp3's using K3b you will need to install libk3b2-mp3 or consider using KAudioCreator
Other Usefull Links:
Windows to Ubuntu Transition Guide: http://www.pcmech.com/show/os/917/ This is a usefull transition guide to read if you are new to linux, even if you don't intend to use Ubuntu or any of it's siblings.
The official guide can found here, and is packed with lots of usefull friendly information to get you started, and is also a good reference guide.
Ubuntu and Kubuntu use Adept as the Package Manager for installing software, however I would recommend installing and using Synaptic as the GUI Package Manager. For the command line interface (CLI) you use apt-get to install/upgrade/remove additional software.
You can also use the sources.lst generator to build your repos, but don't use it if you have nvidia or ati grahics cards.
If you want to use the command line interpretor to look for packages then the following might come in handy:
Show a list of packages: dpkg -l
Searching for a package: apt-cache search <whatever> or dpkg -S filename
If you are looking to see if a package exists in the repositories then enter the following into Konqueror: apt:/
If you are interested in taking linux for a test drive, but don't want to actually install it to a hard disk then take a look at: http://www.livecdlist.com/
If you are having boot problems try SmartBootManager