About Sorting large Xml Files

Hello,
May be this place is not for this sort of questions, but i'm really
helpless.
I've been trying to sort a very large Xml file around 500 MB, can be more
than this, but cannot find out a better solution which can use less of my
resources and give me some good results. Any one who have done this before?
Even reading/writing takes alot of time through SAX and DOM. then i've to
use my own logic to sort out the data.
Thanks alot!

Regards,
Saqib Javed