[SNYPE00]

Personally Im not convinced that tweaks work for cable/dsl, but here would be the place to go: http://www.speedguide.net .
Make sure your machine is not the problem first. Have enought Ram, plenty of free space (delete those temp files), turn off progrms that dont need to run (check the sys tray), before blaming the connection.
All ISPs oversubscribe their services and we end up with connections that vary depending on how many users are on (YES Dsl users, it happens to you too!!).