postgreSQL functions and postgres JDBC

Hi,
I'm looking for an "easy" way to change DB server from MS SQL Server to
PostgreSQL. The site is using servlets that calls stored procedures.

As I understand it postgreSQL functions can only return a basic datatype
while stored procedures in MS SQL Server return recordsets that can be
retrieved from the Jdbc:Odbc bridge into Java ResultSet:

ResultSet rs=cstmt.executeQuery();

My question is: How does this work with postgres JDBC. Do your just make a
CallableStatement end execute the query (name of the function and
parameters) the same way, and if so, what do I get back? A ResultSet with 1
row and 1 column?

Greatful for an answer.

/Per