I have tried Kubuntu on my pc (i have a celeron d 352) it was alright at completing the tasks you have mentioned, find more info about it at...
http://www.kubuntu.org/
A live cd enables you to use/preview the software (operating system) whilst you can still use your current operating system as it doesn't affect the current running os, it just 'runs on top of it'.
generally you put the live cd in your pc and boot from it, the software intalizes and you are able to preview it. then if you reboot the pc, take out the cd, you can carry on using your other operating system