I've noticed that the 160GB drive in my new MBP C2D is very sensitive to vibration... when using the machine in an environment where there is a lot of vibration (like the live roon of a recording studio or at a gig) the internal drive seems to slow down... Logic's Disk meter starts to creep up until it's craps out...
I found that putting some rolled up tissue paper under the machine rectified the problem, these were acting as simple shock absorbers. It's a bit of a pain, as in these situations I'd prefer to not lug my external firewire drive around... or put tissue under my computer! Is it a duff drive or have others experienced this?