I believe you can use whatever size switch you want. However, Isn't the limit of halo 2 still 16 players per "server." If you just want to get a bunch of people together for a Halo2 lan then I'm sure you could use a 16 port w/ 16 xboxes and either have everyone play on their own tv or have multiple games going at once. You just wont be able to have more than 16 per game, though you could have 16x4 people playing off the same switch at once... you'd just have 4 huge games.