Difference between Oracle jdbc driver classes?
For Oracle 9i onwards you should use oracle.jdbc.OracleDriver rather than oracle.jdbc.driver.OracleDriver as Oracle have stated that oracle.jdbc.driver.OracleDriver is deprecated and support for this driver class will be discontinued in the next major release.
-- http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html#Oracle_8i,9i&_10g