My comp's a AMD64 2600+ with overclocked GF6600GT, and a gig of fast-enough-damnit ram; so there's no problem there.
The problem is that the MX1000, being 800 DPI, is far more senstive than the MSoptical I had (which was about 3 DPI), meaning it's too hard to aim, and putting the sensitivity in my CFG file below about 0.7 makes the mouse only response to huge movements.