After spending many hours on this issue I'm ready to give up and go and buy Win7 instead.
I was able to get the backlight to work for a short while, but without warning it stopped working. No idea what changed, I didn't install anything between when it worked and when it stopped working. Hitting the backlight keys now brings up the backlight indicator on the screen and sends it into an eternal loop (flashing repeatedly). After that, all keyboard input is dead, so the system has to be rebooted before it can be used again.
As for the wireless, status quo: if the network is idle for a minute or two the wireless goes down and it takes a long time for it to get back online (with network key dialogs popping up in between etc). If I start ping in a bash terminal right after booting, the wireless stays up but as this is my wife's notebook that is not really practical. (She said "Do I really have to do that all the time?!")
Anyways, I just wanted to follow up with this status update. I also want to extend a big thanks to all volunteers who spend their time, money, blood, sweat and tears on running this forum and on trying to get Ubuntu to work on all systems.
I will definitely try installing Ubuntu on that system again later. Right now however I just need to get it up and running before my wife strangle me... (She asked me this morning: "I have had that computer for two weeks now, why does it still don't work?", so I guess that is a hint that it is time to fall back on Windows...