First little joyful fact: SuSE 11.0 replaced the Ubuntu and not the SuSE 10.3 GRUB; took me a while to realise that, and a GRUB crashing at stage 1.5 or failing to read the system partition is not a pretty thing. Also, even the working version completely ignores the Windoze and Ubuntu installs. Still, one can fix that.
Secondly: SuSE boots, X doesn't start. At least I had a root shell and a network connection. xorg.conf had no mention of AIGLX options, so I started the console yast (old and staunch friend), added the ATI repositories, did an update, installed the fglrx driver and ran sax2. rcxdm restart resulted in a graphical login screen. Phew!
Thirdly: no users. I could have sworn I imported the old ones during installation. I logged in as root, created the users again in yast and gave them their old home directories, which remained unchanged, thank God.
Maybe it's Xanthippe, the little bitch, and her ATI Radeon X1300, or I was just extremely tired and stupid during install, but this could really have gone more smoothly (cf. Persephone).