Microsoft announces the first Windows Vista Service Pack, which brings 23 security updates and 550 hot-fixes. A large number of individual files and components have been updated for SP1 and language files for the 36 basic languages are included in the standalone installer.

This SP1 is delivered to the Microsoft servers in a stand-alone package of 430 MB. However, most home and small business users will receive SP1 via Windows Update, which utilizes an efficient transfer mechanism to download only the actual bytes changed, resulting in a 65MB download.