Doubling the speed of Vista is very easy: uninstall it, and install windows XP instead.* Now you've doubled the speed of your computer and got rid of all the Orwellian controls that were put into Vista! Don't worry though you don't need any of Vista's advanced security features because they've all been cracked already, and would now taking up resources for nothing.
(*Before you do so, make sure you back up all your data and check your hardware is compatible with XP.)
Once you've reinstalled Windows XP then stick in “Windows Blinds” or other such software that lets you skin the interface. You can then give your computer a nice Vista look, while at the same time having all that raw processing power free and available on your computer to do something more useful. (More useful than Vista polling the hardware to check if you're trying to steal any “premium content” 20 times every second.)

There are also third party utilities that can give you all the fancy 3D effects of windows Vista, as well as other effects such as Beryl style desktop cubes which also help to increase productivity. Third party vendors provide all the security Windows XP needs with the advantages that if any one security product becomes too bloated, we can switch to a new provider since it's not integrated into the OS like the integrated security systems in Vista.
Alan Turing originally envisaged computers as being machines which could be programmed to emulate any other machine. Microsoft hope to take that away, but limiting what software runs using DRM and other intrusive technologies. By using XP you are keeping control of your own computer and are sending a message to the Microsoft - Hollywood Cartel that they cannot subvert Turing's original and enduring vision for computers as open systems.