>>95996807
Player book wise, PHB1 and PHB2 are the go to books for baseline player options. PHB3 is fine, but the opinion on Psionics is split, and the non Psionic classes in the book are half baked at best. You might also consider the Adventurer's Vault if you want more options for magic items, and some of the Powers series of books for more player options potentially too, but I wouldn't say they're necessary for play in the beginning.

DM book wise, DMG1 and 2, Rules Compendium, MM3, Monster Vault and picrel. You don't really need much beyond this to run the game, but other options are out there, and picrel will make older MM books viable to use somewhat.

Have fun Anon! Let us know how your game goes!