By default, Windows XP reserves 20% of the connection bandwidth for Quality Of Service traffic. If the system uses more than a single adapter for network connections, each adapter may be set individually by navigating to:
Start>Run> Regedit
Go to: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Psched
Modify/Create DWORD Value of Data type REG_DWORD Named [NonBestEffortLimit]
Setting for Value Data: [Enter as a Percentage / Default Value = 20]
Exit Registry / Reboot