Comments only on Fuji S2. It's worlds ahead of the S1 in every respect. More information, better color, wider ISO range, better flash program. I could go on, but why?
If you already have the S1 body, what makes sense now is to start building a system. Your next step should be the S2 (or S3 when it comes out). Then, start expanding on lenses. Right now, I have a Tamron 28-75 2.8 lens for general purpose. But for brutally tack-sharp pictures, I use the Nikon 60mm macro or the 85mm f1.8. I also have a 180 Nikkor and a 500mm (manual) Nikkor.
While other lenses are good, you can really see the difference on the S2 when you use the best glass.
An alternative would be to get the Nikon D100, but if you like the overall Fuji feel, the S2 is a great camera.
Long term, you'll save money by staying in the same lens family, because it will allow you to branch out instead of duplicating, which you would be doing with the Sony.