People, don't misslead other people with advices about not installing SP onto existing OS, because, you just prove your lack of knowledge ... installing SP onto existing OS is reccomended and OK! No one on the face of earth would reinstall production servers with SP integrated into his/her CD! So please don't spread these stupid conclusions because you can create more harm than you even can imagine. Service Pack is to be installed, of course it's reccomended to make a test run on the same or similar configuration prior to the deployment ... any issue with service pack is considered as security issue, and that call is free with MS support!