I dont think Twilight Princess is the sequel to Ocarina of Time. In Twilight Princess, Link is a farm boy. In Ocarina of Time Link is a kid who was raised in a forest villiage of the Kokiri.
Wind Waker was the first Zelda game to make it clear that the one called Link, the Hero of all Zelda games, is not the same person from one game to another. Not all Links are the same, so all the Zelda games dont have to have a direct sequel.
If you have a Gamecube (though you wont necessarily need one when the Wii comes out), there is a game that you can only buy used because it wasn’t originally supposed to be on shelves for its own purchase. Its a game disc that has 2 versions of Ocarina of Time. One of them is Master Quest, which is alot of the same, but the only difference is the dungeons are harder. They were both released for the N64, but Master Quest never reached American shores, so Nintendo put both games on one Gamecube disc as part of a promotion deal (buy or reserve “this” and get a copy of “this bonus disc” free).