Hello and thank you for using just answer. I'm sorry to hear of your troubles. I worked for saturn for several years and have dealt with these transmisson issues, Saturn was GM's experiment company for the variable transmission, as you know if failed miserably and saturn only had it in production for 2 years before discontinuing. A lot of the ones that were produced were either bought back or repaired several times while under warranty.
Yes you could install a regular automatic transmission in this vehicle however it's not as simple as it sounds, to accomplish this you would have to replace a lot more then just the transmission since it's all electronically controlled. By the time you swap wiring harness, computer, linkage, mounts, etc, etc.....this would be an incredible cost to accomplish. My recommendation on swaps such as this has always been to find a salvaged vehicle that you can swap parts from if you are going to have it done to reduce cost. To answer your last question, saturn was very good about responding to the variable transmission issues while the cars were still under warranty, being 6 years old there is nothing they can or will do now. From what I have heard they have limited parts availability on these units now as well.