Good News! Windows Vista includes TCP Autotuning. It will use up to a 16 MB maximum receive window. If anyone knows how to increase this above 16 MB please let me know.

Vista also includes "Compound TCP (CTCP)", which is similar to cubic on Linux. To enable this, set the following:

    netsh interface tcp set global congestionprovider=ctcp" 

If you even need to disable / reenable autotuning, here are the commands:

    netsh interface tcp set global autotunninglevel=disabled
    netsh interface tcp set global autotunninglevel=normal
    

Note: You'll need to Right-click "run as administrator" for these to work.

There is no way to adjust the default TCP buffer in Vista, which is 64 KB. Also, the Windows Vista autotuning algorithm is not used unless the RTT is greater than 1 ms, so single streamTCP will be throttled on a LAN by this small default TCP buffer.

For more information, see these articles:

TCP Receive Window Auto-Tuning in Vista

Enterprise Networking with Windows Vista

Why TcpWindowSize does not work in Vista