> I have downloaded <Xalan-C_1_8_0-src.tar.gz>   from  www.apache.org
> I have to compile it and rebuild it for 64 bit architechture.Which
> files are to be considered for rebuilding.

There is a user list for Xalan-C where you can ask such questions:

http://xml.apache.org/mail.html#xalan-c-users

Please subscribe and post whatever questions you have there.  Also, please 
make sure you've read the included documentation regarding the build 
process before you post.

Dave