Windows XP reserves 20 per sent of your Internet bandwidth for Quality
of Service, Automatic Updates, Firewall updates etc...
This is unnecessary, & can be disabled:-

!.) Open Group Policy Editor(Only for XP Professional users not
available in XP Home) by Start > Run > gpedit.msc > [Enter]

2.) In the left-hand column in window, navigate to Computer
Configuration > Administrative Templates > Network > Qos Packet
Scheduler.

3.) In the right column, double click "Limit reservable bandwidth" &
select "Enabled".

4.) Change The "Bandwidth Limit" to 0 & click OK.

For XP Home Users
For home users just do this manually.


1.) Go to Start > Control Panel > Automatic Updates

& Start > Settings > Control Panel > Automatic Updates( if you
use classic style start menu)

& turn them Off.

2.) Go to Start > Control Panel > Windows Firewall

& Start > Settings > Control Panel > Windows Firewall( if you
use classic style start menu)

& turn them Off.

Note:- This tricks increase most speed with professional version
because Group Policy Editor automatically stops every service which
need bandwidth.