Arsalan,
We don’t ship JEE 5 libraries yet (renamed by Sun instead of J2EE 1.5). But I have used MyEclipse to work on a JEE 5 project, what you have to do is:
0) Download and install a JEE 5 compliant application server like Glassfish or Sun Application Server 9
1) Create a new J2EE 1.4 project
2) Create a new User Library (Window > Prefs > Java > Build Path > User Libraries) that contains the libraries from your app server (JEE 5 Libraries)
3) Remove the J2EE 1.4 Library Set from your build Path and add the JEE 5 Libraries to your build path.
4) Make sure your complier level for your project is set to Java 5
And you should be all set.