First, to make X run at least with Intel GraCard, I would switch off Ati GraCard in Bios and boot then only with Intel.
Let's see, what will happen then.
If it works, you may install SL on your hdd it with that (switch-off) configuration.
If you can boot then from hdd, then renew (update) your repo (I assume Weekly).
Search in Rigo then, which Radeon drivers exist. Maybe you can compare while searching in Google, which Radeon driver might be the most suitable one for you.
When found, you should install the matching one to your Kernel number, maybe other, depending modules.
After this install procedure, shutdown, switch Radeon GraCard on in your Bios and reboot.
Let's see what will happen. That is the way I'd try to solve my problem...
-Linuxfluesterer (I love KDE ...)