Thanks Andy_v. Yes, that's why I highlighted that bit; the radeon & fglrx modules shouldn't be loaded or used simultaneously. The fglrx installer or aticonfig usually take care of blacklisting the radeon module & generating the xorg.conf, but since it can't find a supported adaptor it doesn't do so.
I've also tried extracting & patching the fglrx installer, but I'm probably just beating a dead donkey trying to get this to work without the fglrx driver being fixed properly by AMD. I'll keep trying things & look into those links you provided, Andy_v, thank you.
Bridgman, if there are any AGP hotfix patches I could test for you I'd be very happy to do so :), or if you need any more system details just let me know.