Dunno if that could help...
But, IF your mouse gets its valuable 'interface stepping routines' out-of-the-box (so, to speak) it is pretty much evident to me that the problem would have more to do with how Vista keeps tab over it even when in fullscreen mode with the latest Nvidia drivers.
The tricky case i'm trying to make with the above is that, invariably, when the OS unlocks (or reserves it, in a sense) the required heap for the game, it absolutely must do so within a reasonable gigabyting-sysbased-gap to
PREVENT the GC_memory hugs (if there are any or some, btw) to overflow the pagefile (or the inevitable faults the swapping process is always causing, beyond the scope of minimal pagefile sizes or not).
Thus, when the mouse streaks in at nano-speeds, the game has to detect it from & with the proper location variations; a) The mouse driver hands over 'bad' references for the necessary coordinates --or--

Vista can't keep up since the swap interferes.
One more thing... DOM processing (and how it is configured by Vista or you) can actually wreck the scroll function big time. Sadly, there is no workaround for this since that is hardware wiring... but there's still hope; a reconfigured layout for the effective grid pixels of the mouse trails
MIGHT (and i say this for a reason - 3 bits away and you'd shiver the cursor everywhere outside of GC too!!) recover enough speed to fix the issue.
- Zyxpsilon.