I was reading up on 64 bit and comparsions to 32 bit. This is a few links with some highlights that stuck out. If you have an IIS / 64 bit or 32 bit running on 64 bit story, link, pass it along.
Two posts by Thomas Deml
How to enable 32 bit worker processes
-32-bit processes running under WoW64 get 4Gb of addressable virtual memory.
-kernel memory isn’t sacrificed to squeeze out more VM for usermode processes. (Even with 32bit IIS worker processes, the kernel runs native 64bit.)
Microsoft.com Moves to x64 Version of Windows
Note: IIS version 7.0 will provide a supported method to run both 32-bit and 64-bit worker processes simultaneously on the same server.