Is SEGA SPORTS making for cube. Also what good games are coming out for cube??

sega sports is going to make the nfl and nba series on the cube, but not until next year.

As Deftones said, Sega Sports will be on the Gamecube next year. There are a ton of good games coming out. Just for launch there is Star Wars: Rogue Leader, Wave Race Blue, Luigi's Mansion, Super Smash Bros. Melee, Madden and Pikmin that look great. In the future you can expect games from almost all third party developers, maybe even Square, the excellent Rare (donkey kong, banjo, perfect dark, etc.) games will be exclusive, and then you have Nintendo's great first party line-up (mario, zelda, metroid, etc.)

Do I need to by a memory card? I never bought one for the n64.

you will have to buy a memory card for gamecube as the games are on discs not cartridges so they can be only read and not written unlike cartridges which are more like floppy discs in the aspect that they can be read and written with the same hardware and you dont need an extra part (ie. laser) like you would to burn info onto a cd although there is the possibility of them building in a memory card to the gamecube I dont think that will ever happen because they can make more money selling it seperate.