Bigtim,
Are you using the console client? If so, make another directory, copy the fah504-console.exe to it and then go to command line and run
(this is all assuming you are running your current client on core 1 (most likely)
fah504-console -local -config
answer all the questions and when you get to the advanced options answer yes, leave everything at defaults except for MACHINE ID, set that to 2.
With it set at 2, you will see 2 fah process running in task manager each at 50 % max.
I run a similar setup (64x2 5400 4 gig ddr2 ram) and yes with 2 cores running, you will start cranking out some WU's and pts. Also, make sure you have good cooling, it does increase heat a bit.\
Kevinw, I'm no expert in any way on how WU's get assigned, but maybe try setting some of your settings to allow WU's larger than 5mb (by default this is off). Also, you memory might be restricting what WU's you are getting.