Any truth to this...

XP seems to want to reserve 20% of the bandwidth for itself even with QoS disabled. So why not use it to your advantage. To demonstrate the problem, start up a big download from a server with an FTP client. Try to find a server that doesn't max out your bandwidth. In this case you want a slow to medium speed server to demonstrate this. Let it run for a couple of minutes to get stable. The start up another download from the same server with another instance of your FTP client. You will notice that the available bandwidth is now being fought over and one of the clients download will be very slow or both will slow down when they should both be using the available bandwidth. Using this "tweak" both clients will have a fair share of the bandwidth and will not fight over the bandwidth.