While MP3 players bring your home music library with you wherever you go, the home entertainment center still needs to be fed an audio signal from your computer or DVD/CD/MP3 player. Assuming that you are using a DVD/CD/MP3 player, there is still a limitation to the amount of MP3s that you can access at one time because of storage media.
Hooking up a computer, on the other hand, raises the limit of stored MP3s to the capacity of your available hard drive space. The problem with using a computer as the basis for the storage medium of your MP3 music library is that your home entertainment system is still stuck with the problem of how to select a specific track to play or manipulate your music library. Even if you have a remote for your computer, you would need a monitor hooked up or a video out fed to your television to know what you are doing. Either way, it would get very complicated.
Currently, there are a few solutions on the market to meet this exact purpose, but as of CES, several popular products have popped up, including the Sound Blaster Wireless Music from Creative Labs.