@som99:
With "internet on the A500", do you mean internet as a working tcp/ip stack on an A500 connected to the internet, or is it in layman terms as in "web browsing on an A500"? The latter takes more hardware and software to accomplish than the former.
As you live in sweden, the easiest thing would be to buy a 3.1 kickstart from
www.ggs-data.se. You could probably get the 3.1 workbench disks from there too. If not, get it from
www.vesalia.de (inside the eu). And as jkirk said OS3.1 is the most recent version you can run on clean A500 as 3.5 and 3.9 requires a 68020 cpu at a minimum (the A500 has a 68000).
If you are gonna pull this of though, you will need to know some about how to use the amiga workbench and software for it.
/Patrik