You're right in thinking that your CPU temperature is on the high side. This may be causing the CPU to throttle back and cause system slow-down. Before spending money replacing something, try the following:
The CPU heatsink fins are probably clogged with dust. This is a common cause of overheating. Remove the fan, clean it AND the heatsink. Use a paintbrush to clean between the heatsink fins. If you can't remove the fan, at least use something like a bicycle pump to blow out dust.
As comp@ddict suggested, remove the CPU heatsink, clean the old thermal paste and apply a fresh one. If you're not familiar with how to do that, ask for help from someone who knows how to do it.
Are you familiar with memtest86? You can check your memory with it. Download it from here:
http://www.memtest86.com
Use it to burn a bootable CD and boot your computer with it. At default settings, it will automatically run your memory through 8 different tests and report any defect. Preferably let the cycle of 8 stages run several times (it will automatically repeat the tests until you stop it).
It will be a good idea to report your results here.
My System Problem
Re: My System Problem
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