The difference between sound cards for music and games?
All gaming sound cards (Creative.. anything by them. I don't care if it's X-Fi Fatality or Music or whatever they call them. Anything from Creative is for games) will sound more bloated. The bass will not be as detailed, and will sometimes overpower the rest of music.
Music sound cards, however, particulary the EMU 0404 (which is actually made by Creative, but not plastered with the X-Fi jibber jabber), will sound more flat, ideally at least. Flat? Nothing overpowers anything. Is this exciting? No. But, it allows the end-user to enjoy the system being listened to. Ideally, there will be no coloration from the sound card.
Music sound cards typically don't have "EAX" support or any of the other techno babble associated with gaming cards.
Another thing to consider is the DACs (digital-to-analog converters) built onto sound cards. All gaming sound cards mentioned above and on this forum are built onto the card. This means if you ever plan on using external amps or DACs, the sound card will interfere with the rest of your equipment's processing.
Music sound cards, however, only deal with the digital signal. As a result, there will be less ground noise (that is, hissing caused by fans in a computer). This is because the conversion to an analog signal is done externally, outside the computer and away from the fans circulating air.