Dude AVISYNTH to the rescue. Read
ErMaC & AbsoluteDestiny's Friendly AMV Guides will get you stared anyway
I'm (unfortunately) living in PAL land... didn't think you were too but eh shows what i know.
vdub is supposed to have a smart deinterlacer built into it... I don't have it but I'm sure there's a link for the plugin somewhere (someone gave it to me)... I prefer to deinterlace using avisynth anyway since it gives me more control over the different functions.
Now I don't have a mac, so can you use vdub/avisynth on a mac?