As far as I know, PPro (both Win and Mac) capture digitised tapes into the DV AVI codec... on Win it is AVI and Mac it is MOV... but the internals are the same
What is your digitising device... and does it come with it's own software?
But, do be aware that the DV AVI codec, at about 13Gig per hour, is as good as it gets for editing
If you do use other software to capture to a compressed format, you lose a great deal of the original picture quality
I hope this old link is still active... Why not edit mpeg http://tangentsoft.net/video/mpeg/edit.html