I DLed the Speedfan program, here's my screen shot.
The CPU temperature is similar to what I've had for years now so it doesn't strike me as an issue, even though there is a flame icon next to it.
I don't know what the Core temperatures are, how could the CPU cores be 75C and the CPU at 51C?
I also have no idea what the AUX temperature is, that is the one that scared me so I checked at the temperatures in the BIOS and no number like that came up, my GPU temperature reported by the ATI control center is 64C.
The only thing I can think of is that my power supply is starting to go out which was reinforced by another forum post I saw elsewhere on a similar topic, the computer may not be able to receive enough power to go on if the GPU draws too much power to handle more powerful graphics. So when I look at this Speedfan data I noticed that the +12V rail is under 12V and I'm currently idling.
I will buy another PS but I'd rather not spend the money on only a weak basis.