In a large bowl, cream together margarine, white sugar and brown sugar until smooth. Beat in the eggs and vanilla. In a separate bowl, mix together flour, bicarb soda and salt. Add to egg mixture and mix well. Stir in chocolate chips. Instead of just dropping them onto the baking tray, I roll the biscuits into balls - it makes them all look very uniform and nice!
Bake in preheated oven for 12 to15 minutes, or until light brown. Cool on a wire rack.