i bought an el cheapo HSF with a heat pad on it for my AthlonXP 1900+.
Now even WITHOUT any overclocking the ah heck was unstable and hot as anything.
Bought a pure copper HSF and an huge 7500 rpm fan + hi quality thermal paste, all works fine now, although I've decided there's no point overclocking this system now
For your question, try leaving the pad ON, if your system works, then hey there's no need to change anything. BUT, if you're system is horribly unstable and locks up frequently then change the HSF to some noisy (but effective) alternative.