Windows Server 2008 R2 is 64-bit ONLY
Just in case you are wondering.
Here is a technet blog post about it:
http://blogs.technet.com/windowsserver/archive/2008/10/28/announcing-windows-server-2008-r2.aspx
…and a little more on the subject at Brian Madden’s blog:
Categories: Server 2008, Windows Server