How big is SP1?
That depends on how you get it. The standalone updater for the five-language version weighs in at 434MB (455,562,200 bytes) for the x86 version, and 726MB (761,740,600 bytes) for the x64 version. If you download the installer via Windows Update, however, the package is much smaller, typically over 50 MB but well under 100 MB. The updater uses Remote Differential Compression to compare the currently installed OS files with the SP1 files on the server, downloads the changed portions from the Windows Update server, and then combines the updates with the unchanged contents on the computer being upgraded.
The 32–bit standalone installer is approximately 60% larger than Windows XP Service Pack 2. Delivered via Windows Update, Vista SP1 is slightly smaller than the Windows Update version of XP SP2.
Will SP1 install on my copy of Windows Vista?
Yes, as long as you have a retail, OEM, or Enterprise edition in English, German, French, Spanish, or Japanese. If you have any other language packs installed (in Vista Ultimate or Enterprise), you’ll have to uninstall them first. A standalone updater for all worldwide languages will be available in April.
What are the file names and MD5 hashes of the standalone updaters?
The following information applies to the standalone 5-language packages:
x86 (32-bit): Windows6.0-KB936330-X86-wave0.exe
MD5 checksum: d597866e93bc8f80ecca234c4e9ce5a2
x64 (64-bit): Windows6.0-KB936330-X64-wave0.exe
MD5 checksum: 983308426e8ee7649f53b41f4e5c42d4
How long does the SP1 installation take?
Usually under an hour, assuming you have reasonably modern hardware. Some people claim to have completed an install in less than a half-hour; an upgrade that takes significantly longer might indicate problems with installed hardware or software.