personaly, i use both. I have a yahoo account for my email so i naturaly got YM. Its good for IMs but the call quality is terrible and so is the vid quality. I also got skype because i have a few friends who refuse to use anything else. It has much better call and vid quality and you can call land and mobile phones. there are pros and cons to each but i would suggest getting both. my guess is that you would find more people that you know with yahoo messenger because it is a common email. skype is just an IM client