[Gregstrom]

I'd say go with Windows 7, as the only other retail option is Vista ('nuff said).

If your budget stretches to one of the Acer Gemstone Blue variants, I'd recommend it on the grounds that mine is a good performer.

Try for 4 gig of RAM and a decent processor, natch.

Graphics: You don't need much for Dominions, but if you can get an ATI or nVidia card it'll be nice.

As I'm not very good at thinking in Euros and laptop prices tend to vary with location, I don't know how far your budget is likely to go.