The most recent useful information on this card I can find is here:
If I understand this right, and there's a good chance I don't, the Kworld 120 is not supported in the kernel found in Mythbuntu 8.04. But I think it might be in the kernel in 8.10. That is 2.6.27-7.
Rather than update the kernel, I tried installing the 8.10 Beta released last week. I actually had problems installing this, and ended up installing Xubuntu 8.10, then installing MythBuntu.
The card now gets recognized as analog /dev/video0 and as a DVB device. I can run a channel scan on analog and ATSC, but no channels are found.
Does this mean I still need to update the firmware?
I tried following the firmware instructions found here,
but the script gives many errors, leaving me at a dead end.