>> X5000 and year 2005 Powerbook G4's are all in the same performance realm

> As to the P5020 being SO much worse than the G4, I really don't think that is the case

I don't think "same performance realm" means "much worse".

> It has a clock speed advantage

Yes, that's what takemehomegrandma says makes up for its lack of AltiVec.

> AltiVec [is] only a small group of routines

Yes, but definitely of significant advantage for tasks like video decoding.

> I don't like the idea of wasting a huge part of my cpu power on video decoding

I'd love to waste the power of my 2nd CPU on video decoding. Currently, I'm wasting it on doing nothing at all ;-)