Watch out - this advice is useless if you're using Hibernate 3.  

Most notably, it won't do anything because you need:

    <property
name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>


Also, Hibernate 3 supports more c3p0 configuration parameters, so they
will overwrite the c3p0.properties ones.

In Hibernate 3, this is all that I needed to get rid of the crappy
"Software caused connection abort: socket write error":

    <!-- Connection Pooling -->
    <property
name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

    <property name="c3p0.max_size">100</property>
    <property name="c3p0.idleConnectionTestPeriod">300</property>

Ryan