This autotuning fix is definately something to try if you are experiencing slow network/internet speeds in Vista / Windows 7 or 2008 server.
How do you run this fix:
To turn off autotuning launch a command prompt as an Administrator (type “cmd” into the Start box, right click on Command Prompt and select “Run as Administrator), then enter the following line:
netsh interface tcp set global autotuning=disabled
Restart your pc after running this command.
If you want to set this back to normal type the following:
netsh interface tcp set global autotuning=normal
Here is a link for more information regarding autotuning from Microsoft.