Go for the SSD. Do not hesitate over the cost. You can always hang a 1tb drive off of a USB port.

I just did an experiment that I read on another post somewhere. I opened 40 apps from my SSD on my 1gb 2ghz Core Duo iMac. That's right, a 1st gen Intel iMac. They all open almost instantaneously. Its really cool. The only fly in the ointment is that a lot of the apps have a dialog box and they all start jumping up and down.