Please note that Bittorrent measure bandwidth in kiloBytes, not kiloBits. 1 kiloByte = 8 kiloBits
Actual speed is always lower than advertised. Check yours:
http://www.speakeasy.net/speedtest/
Get Event ID 4226 patch. The more half open TCP connections, the better.
http://www.lvllord.de/?url=tools
Increase TCP ACK window.
http://www.speedguide.net/downloads.php