I use MSN, mostly to chat to my mother (who lives 3 countries away...) and sometimes my brothers (who live at the other side of the country). Never felt the need to visit any social network site. And I only see a purpose for twitter for companies that are pushing a product.
Oh, my "social network" are forums... I visit 2 daily.
"I followed you."
"Because you were moving. It's impossible to follow someone who is standing still. If I hadn't moved, I would have lost you. Thus, follow."
from: Edge of Destiny