how to configure wsad 5.1 to use jdk 1.4 or above instead of old jdk1.3

[ananth]

if i create a server in wsad 5.1 the new server uses jdk 1.3. how can i
run classes cmpatible with jdk 1.4 or above. or is there any way to
configure the server to look for jdk 1.4 or above instead of using
jdk1.3. can any body help. thanks in advance