>I've noticed this for some time, but it isn't causing me any problems, so I havn't prioritized it as something that need immediate attention. I figured I would come across the meaning of this assumption when I least expect. I've filed this away, so hopefully when the answer about this presents itself I will recognize it.

You got my curiosity up so I checked by boot.log:

<6>Uniform Multi-Platform E-IDE driver Revision: 6.31
<4>ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx

However, before you try changing the mobo bus speed or multiplier setting you might want to read the following info about overclocking, which is what you are considering.

http://www.geek.com/procspec/overclk.htm
JLK