In order to succesfully convert Windows systems to a VMware virtual machine, you need to install the sysprep files of the to be converted host. Below is a list of downloads to these sysprep files:

The base folder of where to put the files is always:

Quote

%ALLUSERSPROFILE%\Application Data\VMware\VMware vCenter Converter Standalone\sysprep

Windows 2000 SP4

• Extract contents to: base-folder\2k
• Available in SP4 or the CD-ROM of Windows 2000 SP4 at Support\Tools\Deploy.cab

Windows 2003 SP2 (32-bit)

• Extract contents to: base-folder\svr2003
• Link: http://www.microsoft.com/en-us/download/details.aspx?id=14830.

Windows 2003 SP2 x64

• Extract contents to: base-folder\svr2003-64
• Link: http://www.microsoft.com/en-us/download/details.aspx?id=8287.

Windows 2003 SP1 (32-bit)

• Extract contents to: base-folder\svr2003
• Link: http://www.microsoft.com/en-us/download/details.aspx?id=23096.

Windows XP SP2 & SP3(32-bit)

• Extract contents of CAB to: base-folder\xp
• SP2 link: https://support.microsoft.com/en-us/kb/838080.
• SP3 link: either use the attached download, or extract it from XP SP3 package (https://www.catalog.update.microsoft.com/Search.aspx?q=KB936929). Microsoft has removed the download link.

Windows XP SP2 x64

• Extract contents to: base-folder\xp-64
• Link: http://www.microsoft.com/en-us/download/details.aspx?id=8287.
  Note that this link is the same for 2003 x64.

For SBS, use their standard counterparts.

Notice

Starting from Windows Vista, the sysprep tools have been built in.

2017-07-24: Fixed several of the download links as they were deprecated.

2011-10-10: I've added several deploy.cab files because the installables do not allow easy access to the files unless you actually install it on a Windows matching the package's OS.