Well I would certainly hope you're right - it's frustrating to have to deal with such irritations on this kind of hardware.
I assume that your findings are based on similar scenarios ie watching 700mb size Xvid encodings, typical

I really don't know what could be peculiar about my setups, after all. They are just stock, vanilla up-to-date Ubuntu installations. And this issue has not been restricted to to any one distribution ....

Nonetheless, there's no harm in trying a Debian install. I'll try some problem files with an installation as not.sure outlines (thanks!)... maybe the wireless 802.11n will even work reliably as well ... and the X composite extension won't freeze the machine ...