Windows Vista has a self tuned RWIN, and it works fine, Microsoft hasn't released much info about specific TCP registry keys yet, but i been testing some of the keys from windows XP. Turned out the Default Send Window also works with Vista.
1.Make sure TCP autotuning is enabled, go to start-run paste this " netshint tcp set global autotuninglevel=normal " and hit enter.
2.Download and install Cablenut Download HERE
3.Disable UAC, go to start-run and type msconfig, click on tools tab andscroll down to "disable UAC" click on it and then click Launch. Reboot your PC.
3.Download and unzip this uploadtweak Download Herejust click on the ccs file and click save to registry in adjuster, If cablenut ask for a OS when your trying to apply the settings, use Windows 2000.
4.Reboot your PC
5.Test speed again.
Good Luck! I, havent test myself yet coz im not a vista users
