JAXP can be used but apache xerces is much better!
I have used it in several XML projects.

u have mentioned that u have worked in several XML projects,
can u please give me few ideas, i mean i want to play with xml so i
want to make some thing that is really a professioanl one.

very good, consider one of these examples:
(these are parts of some of our past and current
projects)

1) reading components initlization data from XML files
2) converting WML to VoiceXML and XHTML (XSTL can be
used also)
3) generating PDF files from XML tables

send another email if you need more examples or
details.