Hi Jojo,
Thanks for the response. I never tried that one, I had both digital and analog plugged in all the time. Maybe I'll try this at home.
I did, however, try a DVI-HDMI cable...still with the same result (black).
After a while of fibbling around the forums I saw something about Live CD working, but not "regular install". I tried to boot a Live version...crappy on vga...but it worked on dvi-hdmi. Once inside live environment, I could choose to install mythbuntu on my machine. And after that, it worked. I have no idea why an "ordinary install" didn't work but an install from live environment did. But as for now, I frankly don't care. =)
/Tomas