Monitoring temperature

You can try the Intel desktop utility. Its made for Intel boards, but MAY work with a Dell with a Intel chipset and CPU.

For CPU temps RealTemp is great. I know its a "Third party" software but its small and accurate.

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I agree with the RealTemp or go with HWMonitor, which provides greater details of the overall system information.

I always find Coretemp to be accurate.

HWMonitor doesn't work on my system. It just displays an almost blank window with the name of the computer. Help has nothing. Clicking on privacy policy links to a non-existent page.

I would go with RealTemp or CoreTemp than. The one advantage to RealTemp is you can calibrate your sensors to get a more accurate reading. I would just stay away from SpeedFan, as in my experience it isn't as accurate.

CoreTemp wants to "make changes to my computer". Why?

What OS are you running?

It doesn't make changes to your system but that is a standard warning coming from Vista or Win7 with the UserControl set at default.

Windows 7. It's a standard warning when a program is making a change.

There is nothing to be worried about when installing CoreTemp. It isn't changing anything, just install the program, which technically is a change to your system  

Which PC do you have?

Dell Studio Desktop 540.

Core temp should work fine. It will ask you if it can make changes becuase it access hardware. I use Windows 7 64bit with a C2Q. does it for me.
I've not tried Real Temp on this machine so I can't say.