Nah, the magic system for the 6th edition was integrated into the basic rules set. So there is no 6th edition upgrade to what you have.
All you need for the 6th edition is the basic rule book, an army, that armies book, an army to fight against, that armys book, GW approved dice, GW approved scenery, GW approved measuring sticks, and you\'d be gaming in no time. Except that you should paint those armies, using GW approved painting techniqes and paint. (assembled with the GW GLUE). But after that gaming goodness awaits! Unless, by then you want to get the newly updated rules for your army, and the ones for your opponents army, but shortly after, you\'ll be gaming!! WHEEEE!
I\'ve heard people say that the 5th edition rules were some of the best, so who knows? Maybe its worth more than I know.