In addition to what has been said, the best way to install a service pack is to use the standalone version and to install them immediately after installing the OS. This is the nearest to having a disk with the pack(s) pre-integrated without having such a disk. Of course, you should install the packs in release order (i.e. SP1 then SP2 etc), even if the majority of the files in the older pack get overwritten by the newer version. If your disk already includes SP1 (as mine does), you can go ahead and just install SP2.