I am using platinum. I am interested in 1440 x 480 because I am trying to render two side-by-side streams at 720 x 480...thus the need for 1440 x 480...I don't want the black bars at the top/bottom of the final render, which I think is what I'd end up with if I used the full HD render size you are suggesting (thanks for your help, by the way).
I can do it in AVI format, but not mpeg-2...guess I'll have to find a conversion program to do it for me...Nero did it (about the only useful thing that horrid software does) but I recently lost my XP-machine (and thus the Nerovision program) so I have to find another solution.
Couldn't you just track motion to create your side-by-sides?
Or if using VMS10 Platinum HD Suite, the NewBlueFX Split Screen MSPS?
An easy way might be if you had a 1440x480, you could just use match media properties in the project settings. That should work in any version of Platinum.