In January I built a custom PC and it worked fine. Around October though I felt how hot the air was that was coming out of the back of the case. I checked the computer temperature in BIOS and found my CPU was ideling at ~70 degrees celcius when my CPU has a max temperature of around 69 degrees. Even after leaving my computer off for a few hours it was right back at 70 degrees as soon as I turned it on.

I brought it in to a local computer shop and they charged me $68 to tell me that, "yes, there is a heat problem in your computer".

Could someone help me deterimine if I just need a more powerful fan/heatsink, or if the problem is more likely with the CPU?

Specs:
CPU: http://processorfinder.intel.com/det...px?sSpec=SL88R
Fan/Heatsink: http://www.newegg.com/Product/Produc...82E16835185125

The fan heat sink you have bought is for a socket AM2 cpu. I would go buy a new heat sink/fan for a socket 775 which is what Intel uses. You should buy one specifically built for Intel CPU's.