yep.. pre-generated stuff is a must. I usually index the monsters manual for relevant monsters, or plain print the monsters stat on paper for easy reference. The same goes for NPC's, and the really complex NPC's I generate in Wizards Character generator and print them with powers and all (I play 4e).
The treasure is always written up in advance too - cause I don't want to slow down the game by starting to roll on tables. AND sometimes you want your players to find neat stuff. Remember placing a cool bow on a npc some sessions ago - unfortunatly for the Ranger in the group - he got away *lol*
A DM screen can also be a nice thing - and you can make your own if you haven't bought one - just write up important info and print those and use a binder or two for the screen. And of course nice battle maps and tokens for traps and ALL the monsters (with pictures) that makes the game so much more fun

good luck from a 30 year GM'ing guy