This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
I think the important question is - what kind of processing do you have to do with the big XML file? For a simple pass through the entire document, extracting specific information, SAX processing will use very little memory. If you have to modify the document structure extensively and rewrite it you may be buying more memory... How big are we talking about anyway? Bill