Ta everyone. I had thought about the lenses. We currently have a Pentax 35-80 plus a 100-300 (which we hardly use, and which is a bit of a pain to carry around) Obviously there is the external flash (we have a sigma) which would probably need replacing as well.
The thing with the lenses though is that, as I understand, you basically need to multiply the specs by 1.5 when used with a digital camera. So, the small lens would effectively be 53-120 which means we would need to buy a smaller lens anyway.
The 18-70 (effectively 28-105 seems a very nice one lens solution.
The pentax apparently underperforms on jpeg (but not RAW) (
http://www.dpreview.com/reviews/pentaxistds/page24.asp) which counts against it.
I'll have a look at the superzoom, but I think the gf wants the control of a 'real' camera.
SMHarman: Yes, we will be visiting a shop to handle the product before buying it. I'm just doing my research to narrow the field down
edit:
this guy speaks very highly of the nikon 18-77 mm lens (as well as the d70/50)