This is a nice little tweak to get 20% of bandwidth back.Microsoft reserve 20% of your available bandwidth for their own purposes (suspect for updates and interrogating your machine etc..).

Click Start–>Run–>type “gpedit.msc” without the ”
• This opens the group policy editor. Then go to

  Local Computer Policy–>Computer Configuration–>Administrative Templates–>
  Network–>QOS Packet Scheduler–>Limit Reservable Bandwidth

• Double click on Limit Reservable bandwidth. It will
  say it is not configured, but the truth is under the
  ‘Explain’ tab :

  “By default, the Packet Scheduler limits the system to
  20 percent 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 00.

  This will allow the system to reserve nothing, rather
  than the default 20%.

• works on XP Pro, 2000 and 2003. Also works in windows vista ultimate ( i think, coz m using the ultimate)
  

Here are the screen shots -

cheers