I'm thinking that a P4 will be generally better for video editing (at least, it tends to win in video encoding benches).
If you do decide to get a P4, I'd recommend the 2.4GHz (533MHz FSB) with an ASUS P4PE (i845pe chipset) mobo and 2 sticks of 512mb DDR400. Dont spend too much on RAM, true DDR400 is all you need.