Different MBs read socket-a temps differently. Ambient temp also plays a huge role...
In addition, AthlonXP PCB further exacerbates how inaccurate socket-thermistors are, so XP versus T-bird temps, even on the same MB, aren't possible due to how much better the new pcb is at blocking heat from backside thermistors.
For example, a low-reading mb with a poor heatsink can easily give lower "readings" than a quality heatsink on a hotter reading MB. This is why giving temps that aren't accurate by any means only leads to further confusion... Also, thermistor placement is a big problem... for example, if I bend down the thermistor on my 8kha+, I can "lose" 5C off my temp readings...
Mike