RemoveWGA enables you to remove the Microsoft "Windows Genuine Advantage Notifications" tool, which is calling home and connect to Microsoft servers every time you boot. Once the WGA Notification tool has checked your OS and has confirmed you had a legit copy, there is no decent point or reason to check it again and again every boot.
Also, Windows Genuine Advantage Notifications is different than Windows Genuine Advantage Validation. RemoveWGA only removes the notification part, phoning home, and does not touch the Validation part. As the time I'm writting this, the Validation part is mandatory for some not critical downloads from Microsoft, but the Notification part is not mandatory at all, and you are able to install all of the security updates without installing this one. This may change in the future thought, I don't know what are the Microsoft plans.
http://inc.sie.net/data/RemoveWGA.zip