Following steps will help you to improve the internet speed of Windows XP
Click Start => Run => type “gpedit.msc” without quotes and then press enter. A group policy editor will be opened.
Then go to: Local Computer Policy => Computer Configuration => Administrative Templates => Network => QOS Packet Scheduler => Limit Reservable Bandwidth (Double click on it)
When you double click on Limit Reservable Bandwidth it will say it is not configured. But the truth is under the ‘Explain’ Tab i.e.”By default, the Packet Scheduler limits the system to 20% of the bandwidth of a connection but you can use this setting to override the default.” So the trick is to ENABLE reservable bandwidth, then set it to ZERO. This will allow the system to reserve nothing, rather than the default 20%.