Hello!
I made the changes you suggested in my servlet, that is,

out = response.getWriter();
Context initContext = new InitialContext();
Context envContext = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("java:/comp/env/jdbc/XAOracleDS");
Connection conn = ds.getConnection();
String sql = "SELECT nombre FROM candidatos WHERE id_cand=49851";

and that's the error I get in Apache

error: comp not bound

and the ones i get in Jboss

16:44:07,480 INFO [STDOUT] javax.naming.NameNotFoundException: comp not bound
16:44:07,482 INFO [STDOUT] at org.jnp.server.NamingServer.getBinding(NamingServer.java:495)
16:44:07,697 INFO [STDOUT] at org.jnp.server.NamingServer.getBinding(NamingServer.java:503)
16:44:07,697 INFO [STDOUT] at org.jnp.server.NamingServer.getObject(NamingServer.java:509)
16:44:07,698 INFO [STDOUT] at org.jnp.server.NamingServer.lookup(NamingServer.java:253)
16:44:07,698 INFO [STDOUT] at org.jnp.server.NamingServer.lookup(NamingServer.java:256)
16:44:07,806 INFO [STDOUT] at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:529)
16:44:07,807 INFO [STDOUT] at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:508)
16:44:07,807 INFO [STDOUT] at servlet.DataBaseServlet.doGet(DataBaseServlet.java:41)
16:44:07,808 INFO [STDOUT] at javax.servlet.http.HttpServlet.service(HttpServlet.java:697)
16:44:07,922 INFO [STDOUT] at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
16:44:07,923 INFO [STDOUT] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)

I've tried all the possible combinations, with no success. Is there any other way to solve my problem? What's exactly what I've to do to configure this connection pool?

Thanks again,
Esther

Thanks for the reply, Juha.

Sorry for asking the RAM questions - I've already checked that out on my own numerous times, played around with that, and know the answers. Not sure why I asked that. What I really want to know is what speed processor I'd need to run JBoss. I understand that it would vary based on the application....but are there any guidelines?