Engine Cool, Radiator overheating?!

[Chuckles]

Totally not understanding this one... My heat gauge reads PERFECT while my Radiator boils. I recently replaced both the Water Pump and Thermostat with New Subaru Parts from Tom. I put the stuff in myself, so maybe I messed something up, but its all pretty fool proof from my angle. The springy side of the Thermostat faces toward the water pump and engine block, right?

I drove it a mile or so and the radiator cracked a bit on top. It started peeing out the grill... and no I have not driven it very far. I doubt the Head Gaskets are bad, they have been checked and rechecked including by Tom (He said they will fail at some point due to age, mine seemed fine in Feb 09, or 60 miles ago)... but what is it then? could I just have a bad radiator, its probably factory original. (1992 LS-L 112k Miles pretty good shape though she's 18yro, legal to vote)

I have no strange sounds, and absolutely no gurgling in the reservoir bottle... Help?