edit:: pointed out grammer errors of Yoshindor's, I was quickly told english wasn't his first langauge, so I removed that part, sorry, I didn't know.
Incase your wondering why Nintendo is still in business, it's because of three reasons. One, They have been able to produce all their systems with either a profit or no net loss. To my knowledge, No other video game company has had the right to boast that, and Microsoft hasn't made any real money off of the Xbox yet. Secondly, Nintendo makes Genre's, might sound wierd, but they invented or contributed greatly to a lot of the Genre's we know today. From what I can tell Mario 64 is the first 3D Platformer. Now they're pretty common. And it's a lot cheaper to make new genre's then to make a game to be the best in the current ones. And the Third reason, is that most games that is a Nintendo exclusive end up being really good, especially if they are made by Nintendo or one of their associates. (Even Pokemon is a good game if you can forget about the anime.)
The reason why the N64 didn't have many good games was because it was expensive to make cartridges, that was a big mistake on Nintendo's Management, 3rd party developer's would rather use CDs and save some money. And the Gamecube has quite a few good games, but most of them are just small titles that never got the proper advertisement they deserved. As well as the fact PS2 has the image of the "Cool" system, and Xbox held the "Mature" Audience, both of which Nintendo under it's current management couldn't hope to compete in.
Nintendo has always been the system children can be safe to play on, which was fine when most gamers were children, and Nintendo is now under new management. Now, from what I've seen, the new Management wants to change the image from children only to Fun for everyone, and giving the old school gamers as many of their favorite classics as possible is a good way to start.