It sounds like you've done most of the basics, but there are a few more things to try. What I don't like is that kubuntu live doesn't boot. Do you get to the grub menu? If so, try running memtest for a few hours. Maybe try another liveCD/DVD linux distro, preferable a current release (the MB looks about a generate back from bleeding edge so should have good support in current releases). What we are wanting is some warm fuzzy the the basics are working (power, cpu, memory, video, dvd) under linux.
Maybe pull out the MB manual and go over the bios step by step. Disable frills, be conservative.
Visually inspect all connections again (MB 4- & 24- pin power connectors in particular) for full seating.
Remove TV card to give you a minimal system (case, power supply, MB, CPU, memory, HDD, DVD) and try the liveCD/DVD.
Shotgun steps are: upgrade BIOS, replace DVD drive.
I suggest keeping with the nvidia 7300 video card until you have good hardware. I don't think Kubuntu 0710 supports the 9xxx series without a driver update.