Thanks for the suggestion John. I guess I need to get the Pro version of Vegas as the ‘custom’ buttom next to all MPEG 2 templates is greyed out in Movie Studio Platinum – so I can’t alter the bit rate.
I did find that rendering the PAL footage to an NTSC AVI in Vegas (and then authoring to NTSC in Architect) results in a noticeably better picture and no interlace flicker – compared with rendering to a PAL AVI in Vegas and then authoring/converting to NTSC in Architect.