Microsoft Windows XP reserve 20% of your bandwidth for its own purposes There is a feature in windows Xp (Packet Scheduler) which take 20% of your internet connection bandwidth but it is possible to squeeze an extra 20% out of your internet connection.
Follow these simple steps to get back your 20% bandwidth speed
Go to Start Menu and RUN
Type "gpedit.msc" to open Group Policy
Go to Local Computer Policy > Computer Configuration > Administrative Templates.
In Administrative Templates,expand Network and then "Qos Packet Scheduler".
In the right panel, right click on "Limit reservable bandwidth" and then select "Properties".
In Limit reservable bandwidth Properties, click on "Setting" tab and then enable Limit reservable bandwidth.
Here you can change Bandwidth Limit from default (20) to 0.
Now , go to your Connection properties, select Networking and be sure Packet Scheduler is enabled . click "OK" and the restart your computer.