With many thanks to Sanket for posting this information originally, I wanted to post these links here so that the next time I can save my self the Google search and just hit this post.  These links are for the EN language, but there's a link at the bottom to the full list for all languages.

Windows 2003 Server 32 bit

http://go.microsoft.com/fwlink/?LinkId=81468

Windows 2003 Server 64 bit

http://go.microsoft.com/fwlink/?LinkId=81459

Vista 64 bit

http://go.microsoft.com/fwlink/?LinkId=81423

Vista 32 bit

http://go.microsoft.com/fwlink/?LinkId=81432

Windows XP 32 bit

http://go.microsoft.com/fwlink/?LinkId=81450

Windows XP 64 bit

http://go.microsoft.com/fwlink/?LinkId=81441

For a complete list of all the downloads in all the languages, you can use this link -

http://msdn.microsoft.com/en-us/library/aa578652.aspx