It took me a while, but I got Ubuntu to load again;the Hardy Heron 8.04 this time. I had to tweak some boot parameters and xorg.conf to get it done, but it works. Second Life, however, doesn't like Hardy Heron; the screen redraws and flickrs are hard on the eye, both with the generic vesa vga driver as well as with the ati driver. Second Life does load in Hardy Heron 8.04, but for all practical purposes it's not usable.
Of course, this triggered me to start messing with the VGA driver settings, ATI cataclyst centers, drivers. Of course I had to reboot, and yes, it didn't want to boot anymroe after that. After logon, Ubuntu presented me with the blank screen of death. Sigh.
Restored the xorg.conf again, so weŕe back online, but I can tell Hardy Heron is still beta; it breaks easily!