I am taking a class on Microsoft SharePoint architecture this week. I learned today in the class that the next version of SharePoint will be 64 bit only. If you are going to be buying new server hardware, get 64 bit hardware.
Not only does SharePoint run better on 64 bit hardware, so does MS SQL Server and ColdFusion. You can also take advantage of much more RAM. I believe that 32 bit hardware is limited to a maximum of 2-4 GBs. 64 bit hardware can go up to 256 Terabytes in theory.