How to find a performance bottleneck?

I have a new system that should, I think, be a rocketship, but it's pretty doggy when working with my larger assemblies.  I have a hard time believing that I'm overworking the hardware, yet something is slowing me down.  It's probably a weak link somewhere.  Any suggestions as to how I can locate the bottleneck?  I'm on XP64 and 2007-x64, by the way.

Thanks for your help!

SolidworksAdministration