Hi Hind,
You'll definitely need X11. It should be one of the disks (perhaps the
Developers Disk?) that came with 10.4. It probably installs to Utilities,
but a sure way to test is to open a Terminal and type
~> open -a x11
For what it's worth, I saw the new iXAFS app install and run on an Intel
Mac yesterday.
Cheers,
--Matt