Windows XP by default reserves 20% of the overall available bandwidth. Thus reducing a portion of you available broadband limit.
Here are some quick steps that will remove this restriction by overriding the default reserve and get optimum value for your money. It will hardly take minutes if you are well versed with Windows.
To start with, make sure you have all rights to change your system settings. For this, you will need to log in as a Primary Owner or Administrator.
Once this is done, just follow these steps:
1) Go to Start > Run > type gpedit.msc
2) Here you will see [Local Computer Policy]
3) Expand the [Administrative Templates] option
4) Expand the [Network] option
5) Click on [QoS Packet Scheduler]
6) On Right pane Double-click [Limit Reservable Bandwidth]
7) Check [Enabled]
8) Change [Bandwidth limit %] to 0 %
9) Click [Apply] [OK]
10) Restart your system
Effects are immediate.