First of all sorry for my bad english.

I have a ms access database client/server. it has 25 tables.
the size of the .mdb file on the server is 200 MB.
I have 5 different users with different rights.

I want to contvert the server part to mysql or postgre sql.

My question is wich one is the best choice mysql or postgre?

Tips about other solutions are welcome also.

Either MySQL or PostgreSQL can handle the needs you've described nicely. MySQL has a bit broader distribution, so there are more people that can help you with problems. PostgreSQL is a much more technically capable engine, and it offers many features today that are still somewhere in the distant future for MySQL.

The choice is really yours. Either one should handle that job nicely.

-PatP