I went to my other house and picked up my exploit game :). Anyway, I bought photoshop 7 with a texture plugin thingy and I was wondering if there is a guide for editing .dds, and that other stuff. I want to make a skin mod on halo some day.
Now, this is for the PC version, and from what I understand you want to edit the XBox version, rest assured there is a fix/workaround for this.
There are a number of mods to make the XBox compatible, including HaloCXE. Also, take a look at Mimesis, supposedly it simplifies a LOT of this stuff for everyone.
The reason I did not include a tut for the Halo Editing Kit, is because it includes some pretty good ones in itself. Check them out, I think you'll like them.