Quick Tidbit on SharePoint and 64-bit
I've had a couple of folks this week ask about steps for eventually upgrading their SharePoint 2007 environments from 32-bit to 64-bit. One of the challenges, from an infrastructure perspective, is to allow for hardware and software upgrades without adversely affecting the application topology. In this case, the answer is easy (taken directly from the SharePoint Team Blog)...
Q: Do you support upgrade from 32bit WSS to 64bit WSS on the same server?
A: No, you would need to backup rebuild the server with 64bit servers and software and restore. You can deploy a SharePoint Server farm on a mix of 32-bit and 64-bit servers, provided that you maintain architecture homogeneity at each topology layer. For example, you should not mix 32-bit and 64-bit WFE servers, but you may use 64-bit database servers or for Excel calculation services in a farm with 32-bit WFE servers and application servers.