You’ll want to check out the [url=http://www.missingremote.com/index.php?option=com_smf&Itemid=198&topic=2854.0]Win7 HTPC client: 32 bit or 64 bit?[/url] thread.
I’m in favor of 64-bit for Windows Media Center based HTPCs. The extra memory is used by Extenders (250MB – 800MB per extender) and the WMP library will benefit from the extra RAM for large collections.
