By default, 20% of the bandwidth of your LAN is reserved by the QoS (Quality Of Service) of Windows XP.
To use all the bandwidth, click the Start button and then click Run. Enter gpedit.msc then Click OK. Click on Administrative Templates, Network, QoS Packet Scheduler.
Double click on Limit bandwidth service. If the option Not Configured or Disabled is selected, the default (20%) is used.
Click on and enter 0 in the field limit bandwidth. Click OK.
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