You can not disable nagling just making a regkey do disable it.
You need to activate QoS on Vista because QoS is disable by default.
Go to Start/Control Panel/ Programs and Features...
Now on your left side you see Turn Windows Features
On or Off after that just active Microsoft Message Queue (MSMQ) Server
[you need to active all be under that MSMQ file by clicking on +].
Now you can disable nagling happy tweak guys xD