Ron and Ryan, is the old radiator leaking? A new core would be nice, but might not be necessary if the core isn't leaking. A quick test is to plug the upper and lower radiator hose fittings, fill the radiator with water and check for leaks. I use Oatey pressure test plugs available in the plumbing department of Home Depot or Lowes. It won't be a pressure test, but these systems aren't under a lot of pressure anyway.
If it doesn't leak, I'd rinse it out well with a garden hose inside an out and try using it.
I live in Gilbert, too. I run a 160 degree thermostat instead of the stock 180 due to our hot summers. I keep it in year round because I don't use the heater very often. Sometimes you'll see the 160 degree thermostats referred to as 'desert thermostats'.
If your core doesn't leak but your upper or lower tanks either leak or have dents but are salvageable, send me a PM and I can offer some advice about how to fix them on your own...or you can stop by and I can show you.
Matt
