If you have XP Pro:
- click start > run
- enter "gpedit.msc" and hit ok
- go to computer configuration > administrative templates > network
- click the folder "QoS Packet Scheduler"
- right-click "Reservable Bandwidth", select properties
- Change it from "Not Configured" to "Enabled" and set your bandwidth limit to "0"
- Select OK
- Go to "My Network Places", then "View Network Connections"
- Right-click your internet connection you want this to work for and select Properties.
- Make sure "QoS packet Scheduler" is checked off.
- Close everything and restart your computer.
Now you have 20% more of your available bandwidth to use.
NOTE : Not tested in other OS.