There are a several benefits of moving to 64bit hardware. 64bit hardware supports more CPUs than 32bit hardware. In addition the 64bit hardware can access way more memory than 32bit hardware. 64bit hardware can use up to 2 TB of data, while 32bit hardware will typically max out at 64 Gigs. What is especially important in that 64bit hardware does not have the AWE requirement that 32bit hardware does so all the memory can be addressed natively without having to go through the AWE driver. In addition to allowing software to access more than 2 Gigs of memory natively it allows allows SQL Server to use more procedure cache as I’ve spoken about.
The 64bit system architecture also processes math functions much faster than the 32bit system architecture. Some software is especially excellent at utilizing this additional power including SQL Server and Exchange server.