My second system, the one in which 7 and 8 are bad, has no extra codecs like BlackMagic. Both my machines are intel based. Carey, do your keys look bad right away or only when you render? Mine look bad right away.
To narrow it down further. I have one computer where the keying looks great in AE7 and bad in AE8. But on another computer AE7 and AE8 both look the same with bad jagged edges. I think it is a codec issue as well. Is anyone out there getting great DV50 keys in AE8? Somebody must be, right?