Extra controllers: Like all recent consoles, the Wii ships with just a single controller (well, one two-part controller: one Wiimote, plus one nunchuk). But the real fun of the system is playing the head-to-head Wii Sports games such as tennis and boxing. To do so, you'll need at least one extra set of controllers--and again, that's one Wiimote ($28.99) plus one nunchuk ($12.99). The Wii supports as many as four, but just the one extra controller set should suffice--at least for Christmas morning.

Rechargeable batteries: The Wiimote takes two standard AA batteries. They're included--with the Wii, and with the sold-separately version of the controller mentioned above--but avid players may find the juice draining pretty quickly, especially if they keep the nunchuk attached (it draws its power from the Wiimote). Instead of buying an endless stream of costly AAs, consider investing in a set of rechargeables. You can score a charger and four rechargeable nickel-metal-hydride batteries for less than $25.

GameCube controllers: The Wii is fully backwards compatible with the Nintendo GameCube, but there's a catch: to play the GameCube games, you'll need a GameCube controller ($15.99). You can even go wireless with the Nintendo WaveBird ($59.99). If you already have a GameCube, your existing controllers will work just fine--just plug them in to one of the four ports underneath the flip-up panel on the Wii's topside. GameCube controllers should also work with the Wii's "Virtual Console" games--which saves you the trouble of having to buy a Classic Controller.

GameCube memory cards: One other annoyance when playing GameCube games: your progress can only be saved to GameCube memory cards, not to the Wii's internal memory or to an SD card (we're hoping Nintendo fixes this with a future firmware update). Like the controllers, your old GC cards will work just fine--there are two slots right next to the GameCube controller ports. If you don't have any onhand (and you want to save your games on GC titles), you'll need to spring for a $26.90 (2GB) memory card.

Wii Points: One of the big attactions of the Wii is its Virtual Console, which lets you purchase classic games that originally came from the Nintendo Entertainment System (NES), the Super NES, the Nintendo 64, the Sega Genesis, and the TurboGrafx16. By the end of 2006, at least 30 titles should be available, including Donkey Kong (NES), Super Mario 64 (N64), and Sonic the Hedgehog (Genesis). To purchase the downloadable titles, you'll need to use a Nintendo currency known as Wii Points (similar to the Microsoft Points on Xbox Live), which currently have an exchange rate of 100 points per U.S. dollar. You can buy Wii Points directly through the console's online store, or use prepaid cards (2000 Wii Points) available in various denominations.

SD card: If you're close to filling the Wii's built-in 512MB of storage with your Virtual Console games, you can always expand your available space with an SD card. Nintendo sells its own, but any run-of-the-mill card will do. Fairly spacious 1GB cards are available for less than $20--even less with mail-in rebates--and they'll work in plenty of other gadgets as well.

Wireless access point: In addition to the downloadable Virtual Console games, the Wii offers online "channels," including news, weather, and even an Opera Web browser (head-to-head online gaming is said to be coming sometime in 2007). You can get online for free via the Wii's built-in Wi-Fi. To do so, of course, you'll need a nearby wireless access point or router. Alternately, you can plug the Nintendo Wi-Fi USB Connector into any nearby PC on a wired network, and the Wii--plus your Nintendo DS--will be able to use it to get online instead.

Component video adapter: The Wii doesn't have the graphical horsepower to handle high-def graphics, but it can do DVD-level 480p video, which will look considerably better on large HDTVs. To see the Wii's games in 480p, you'll need Nintendo's proprietary component video adapter, which should run about $20.