Microsoft in Mp3-Network issues

Some days ago, it was discoverer that playing mp3 on Vista with browsing at the same time will slow down your network.

The news was reported by newspaper and Microsoft was forced to respond to the issue.
Take a look at the answers here, but the “interesting” one is:

“Please note that some of what we are seeing is expected behavior, and some of it is not.  In certain circumstances Windows Vista will trade off network performance in order to improve multimedia playback.  This is by design.”

Design ??? Does XP act in the same way ???
Please…. who in this world could design a modern OS that will slow deliberately the network interface?

ops! microsoft!