Since Microsoft does not officially support the slipstreaming of Windows Vista with Service Pack 1, it would be nice if the company made available a standalone all-language DVD ISO of Windows Vista with SP1 already integrated available via its Web site. That's not happening, from what I can tell. But the following three options are available now:

Windows Vista Service Pack 1 All Language Standalone DVD ISO
This is a DVD ISO image and contains both x86 and x64 versions of Windows Vista Service Pack 1.

Windows Vista Service Pack 1 All Language Standalone EXE (English, x86)
Windows Vista Service Pack 1 All Language Standalone version can be installed on any language version.

Windows Vista Service Pack 1 All Language Standalone EXE (English, x64)
Windows Vista Service Pack 1 All Language Standalone version can be installed on any language version.

Note that none of these are required or recommended for single, standalone upgrades to SP1. Instead, use Windows Update.