I am starting to play D&D and have bought the Players Handbook, the Monsters Manual and the DM guide!
Now, with what did you started playing? Where do you find all of the pertinent information to give out to new characters? Where do we find new encounters? Where does new DM find a pertinent guide?
Are those 3 books all you need to start?
Those three books have been out a while and are now heavily erratad, but they're still a great starting place; you shouldn't need anything else to go have fun. (As okeefe said, check the errata for Stealth in particular on Wizards' web site.)
A pretty good place to start for encounters and adventures is the Living Forgotten Realms archive. It's worth googling or checking the forums for reviews, as not every adventure on this page is worth playing, but they're a solid set of early premade adventures with a lot of the detail work already done for you. They'll do well to let you run a game or two to get started.
I'd start with Corm1-1 "The Black Knight", which has easy combats and some light roleplay to get you going, but your personal preferences (and your players') may vary. Also take a look at Core1-3 "Sense of Wonder", Core1-13 "The Fate of Camp 15", or the excellent and funny Corm1-5 "In the Bleak Midwinter" for some light (if violent) relaxation at the fair.
Note that these adventures were all written for the running "Living Forgotten Realms" con games, aimed at regular players and with no permanent character death, so a couple of them might be a bit hard for a new party. Don't hesitate to remove a few hit points from the monsters or delete some of the minor opponents if your players are having trouble.
Heroes of the Fallen Lands, the Rules Compendium, and a DDI Subscription.
The early books are raw. Very raw. They have relics of the older game philosophies that just don't fit 4e. The first monster manual doesn't reflect "proper" monsters (see the rewrites in the Monster Vault for just more fun monsters). The first PHB, while completely valid, has many "fiddly" things that in later writings, were very well refined. The classes and races are not formally obsoleted, but with all the errata that's occurred, there's little point in favouring the book over ddi.
