Microsoft shed a lot of light on Windows Vista SP1 today and what really caught my eye was that stand alone install, which many companies will use to deploy, tips the scales at a whopping 1GB for x86 and 1.5GB for x64. The reason for the large size it that the service pack includes all the languages.
No matter how you slice it that is a serious amount of data to have to deliver over your network and could take some serious logistics for distribution. You are basically talking about an update that is over 40 percent the size of the original install.
Not only that, installing SP1 will require at least 7GB of free space on x86 and 12GB on an x64 machine. It wasn't clear if that was a hard-coded requirement or if that was a recommendation.
When you look at the footprint that is delivered via Windows Update or WSUS the service pack has a much better story to tell, at only 50Mb.Microsoft, Windows Vista, Service Pack 1, SP1 Beta, Vista SP1
Source:→ Josh's Windows Weblog