getTransactionIsolation() causes SQLException - unrecognized configuration parameter xactisolevel

Setup: Postgres 8.0.1 & postgresql-8.0-310.jdbc3.jar

The following code:
---------------------------

try {
Class.forName("org.postgresql.Driver");
} catch (ClassNotFoundException e) {
System.out.println(e);
}

String url = "jdbc:postgresql://dbserver/test";
Properties p = new Properties();
p.setProperty("user", "test");
p.setProperty("password", "test");

Connection con;
try {
con = DriverManager.getConnection(url, p);
System.out.println("con.getTransactionIsolation() = " +
con.getTransactionIsolation());
con.close();
} catch (SQLException e) {
System.out.println(e);
}

Produces this:
---------------------
java.sql.SQLException: ERROR: unrecognized configuration parameter
"xactisolevel"

I've tried:
------------
1.) configuring the default_transaction_isolation parameter in postgresql.conf
2.) setting it programattically via con.setTransactionIsolation()

and now I'm stuck. I really don't care what the transaction isolation
level is. I'm trying to use Postgres 8.0 as a backend database for
Hibernate and org.postgresql.Driver.getTransactionIsolation() is
halting my progress.

Any help would be greatly appreciated.