I don't actually have the game yet, and would love one of your guest passes if you haven't used them yet, but I played the beta and know a little about Protoss strategies.
First I recommend you watch this:
http://www.youtube.com/user/HuskyStarcraft#p/u/29/GpvL5YYPFgc
That strategy will win lots of multiplayer games for you at a low level.