Robert, this may sound ridiculous but the answer depends on what "start playing again" means to you.
If you're interested in just playing the game with your wife or friends your old cards are perfectly fine and you don't really need anything.
If you're interested in playing with some of the newer stuff, there's a bunch of options for you. Ben mentioned a few.
If you're interested in building your own, newbie, casual deck a Deck Builder's Toolkit is a decent option. It'll give you enough stuff to build a couple decks.
If you're interested in pre-constructed "kitchen table" (casual, newbie friendly) Magic, the Intro Packs aren't bad. They also come with a pair of Booster Packs from the corresponding set. Player's returning to the game tend to pick these up to mess around with if their intent is just to "see what's going on now."
If you're looking into playing a bit more competitively (Friday Night Magic, etc.), shoot me an email.