Just thought I'd tell everyone what I ended up getting. The MX518 is great. The laser mice from everything I've read do not seem like a mature technology yet, with lots of issues with different mouse surfaces, and the laser being a bit too sensitive to being removed from its tracking surface (even by a few mms).
I really hated the MX1000, but this 518 is wonderful. It's light, it's precise, it's easy to use in windows, accurate as heck in games. I went with the s&s steelpad as well and with the little mouse glider things on it's wonderful too.
I like light, accurate, chunky mice and the 518 fits the bill like a charm.
Would very happily recommend it to others migrating from the horrid intelli 4.0.