Myth: Windows uses 20% of your bandwidth all the time for it’s own purposes.
Facts: Many technical sites and blogs have claimed this will increase your internet connection speed and that Windows always reserves 20 percent of the available bandwidth for QoS. This is entirely wrong. As in Windows 2000, programs can take advantage of QoS through the QoS APIs in Windows XP. 100% of the network bandwidth is available to be shared by all programs unless a program specifically requests priority bandwidth.