IRC is a lot better than skype! IRC you can have so many different channels and be in a lot of different ones at once. With skype you have to be invited into the chat and also invite every person you want there. too much effort
IRC > skype
less demanding of the computers processing powers, you can easily talk in multiple chat rooms with multiple different people, and with single people as well, etc etc reasons, i only like skype because the actual calling factor.