I do both. I write with my left, and I operate stuff, like keypads, remote controls and anything with both hands. I'm more of a lefty, but bnoth serves me.
I use my right hand to write. As for everything else I use both hands. Kind of hard to use a certain hand at work when you have to get at something from a certain position that you need to use a certain hand for. As for sports and such I can use either.