Crayno: And on a sidenote: does it run on a laptop (XP) reliably?
Totally depends on the laptop. Laptops vary from "Fancy graphing calculator" up through "Portable Cray computer."
As a benchmark, my Dell Inspiron 1200 with a 1.3 GHz processor and a gig of RAM runs the game passably. (This particular laptop has the bare-minimum video card for the game.) It's fairly slow and choppy at the default zoom, so I mainly play zoomed out to the icon level.
I hope that this helps.