Zaistars

For any of you playing 4th ed for the first time. make sure you pick up the player's handbook. None of the other books are necessary, with the possible exception of the new expantion books. Adventurer's vault is good if you want to plan out what kinds of goodies you character wants (called a wish list), and the Martial Power is a good one if you want some extra options for your martial type class (fighter, warlord, rogue, and rangers).
neither are necessary and none of the powers are "more powerful" than the PHB stuff but some are "cooler," as in different. There are a whole host of new feats (which if you've played yet you know is something that 4th ed has made weak in the PHB).
Enjoy guys.