Windows Vista SP1 will support the following delivery methods:

1. Express: Requires an internet connection, but minimizes the size of the download by sending only the changes needed for a specific computer.
   About approximately 65 MB for x86-based operating systems.
2. Stand-alone: Recommended for computers with limited Internet connectivity and for applying the service pack to multiple computers. The download size is (much) larger than the express package, but customers can apply a single package to any Windows Vista version and language combination (within a platform).
   About 450 MB (5 Language package) and about 550 MB (Full 36 language package) for x86-based operating systems.
3. Slipstream: The slipstream version of Windows Vista SP1 is media that already contains the service pack, which companies can use to deploy the operating system to new computers or to upgrade existing computers.  Availability will be limited. Microsoft will update Windows Vista retail media with Windows Vista SP1 slipstream media in the future.

   Some quick facts on what Vista Service Pack 1 will bring (continue at source)