What you're missing is that "XEON" is just Intel's marketing name for many different chips. Your computer uses the chips known internally at Intel as "Harpertown" chips. The newer Mac Pros use what Intel called "Nehalem."
But as far as the customer knows, they're all just called XEON.
So what that means is, since Nehalem chips are newer, they are faster than Harpertown chips, even at the same speeds. So those 2.93 chips are actually faster than your 3.2 chips. There's a lot of stuff going on in there, the processor speed is only one part of the equation.
Here's an article that talks about that EXACT issue: