Here is a better link to the map system:
http://maps.eniro.com:80/servlets/se...523182;6541797
This map is bigger than the last one (490*420).
With "&symbols=star;1523182;6541797" you can show a point in the map with a figure. Perhaps it will make the programming easier. Just remove this part to exclude the figure.
I used the town next to mine, because it show the streets and would perhaps make it easier for you to decide what zoomlevel to use.
BTW the GPS coordinates are of the type RT90 (at least what I believe after testing with some coordinates.).