For a 64-bit database server with:
Up to 10 concurrent users, you require an Intel Single Core CPU (Pentium, AMD, or compatible), 1 GHz or faster
More than 10 concurrent users, you require an Intel Dual Core CPU (Pentium, AMD, or compatible), 1 GHz or faster
For client nodes, the default configuration also requires 64-bit binaries. However, if you require 32-bit client nodes (for example, to allow for the use of 32-bit third-party DLLs), these can be used with some loss of performance and functionality.