Freeze / lockup when starting X in freshly installed F8

[Juergen Botz]

I just did a fresh install of F8 on a system with an old
ATI Radeon 7500 (AGP) board, and the system freezes when 
starting X.  The xorg.conf is just the basic one that the 
install generated... it had the 'radeon' driver for device,
but I also tried putting 'ati' with the same result.  
Putting 'vesa' as the device works fine.

The freeze is a hard lockup, i.e. the system no longer
responds to pings from the outside.

Other system info:
   CPU: AMD Athlon XP 2500+
   MB:  Asus A7V8X (Via KT400/KT600 based)
   RAM: 1.5GB

What can I do to fix or further diagnose this?

TIA, :j