Due to the confusion around running x86 and x64 in MOSS farms and it's supportability, I wanted to take a minute to talk about Windows Server 2003 and Windows Server 2008 machines in one farm. Some of the SharePoint PMs confirmed internally there are no supportability issues around running a WSS 3.0 or MOSS 2007 farm on the two different OSes. (This implies that you are running all machines at the same patch level at or above SP1, because you can't install pre-SP1 builds onto Server 2008.)