I have a Asus p6t SE crossfire motherboard

I have been building it incrementally and now I am getting ram

I am trying to get it up and running as soon as possible then make minor upgrades after its running (more ram, better card, etc)

Its a triple channel board with 6 ram slots , however, for convenience I want to buy a 2 2 gig stick set, for four gigs, and then upgrade 4 gigs and then another.

however 4 gig sticks are dual channel and I dont know If I can use dual channel in a triple channel board?

More so if I add another four will it act as triple channel plus 1 ? if I add just one of the same brand and speed of ram will it act as triple channel ?.