Linux Mint is Ubuntu with all the media and non-free / proprietary software included, plus a shinny chrome look to it.
http://www.linuxmint.com/download.php
Just get the standard 32 bit, it will do everything you want straight out the bag.
Medibuntu is if you want to add a TV card and run MythTV, which allows you to schedule recordings using a select & click EPG interface. You can then stream your recorded TV programs over your home network (even to wireless netbooks). However MythTV can be a step learning curve for someone just starting with Linux. It took me 5 years to man up enough to take on the MythTV challenge.
Ubuntu always requires you to add alot of the media stuff like Chromium (Browser), GnomeBaker, VLC media player, Skype.
Skype can have problems in Ubuntu with the microphone part off web cam. I'm not sure if Skype is better / intergrated in Linux Mint.