terryJones,
New AMD 2.5 Gb processor
If you are running your AMD Processor at 2.5Ghz then you are severely overclocking it. The most I have been able to get out of my AthlonXP 2500+ is 2.33Ghz and I am using extreme cooling.
Take Care,
Richard
P.S. Also, if you reused your heatsink, make sure you reapplied your thermal grease, and make sure you have your heatsink on the right way around, it does make a difference: