I used to have crashes all the time with windows 7 (pretty much every 15-30 mins) but ever since I set the game to high affinity it hasn't crashed once
It has something to do with the dual core systems, simcity 4 wasnt designed for them, so it cant handle it.
Here's the link to do it: www.vistax64.com/gaming/197915-setting-processor-affinity-made-easy.html though it may or may not help you guys.