I have footage from an HVX200 (960x720 1.33 PAR) and a Canon A1 (1440x1080 1.33 PAR).
I need to make them all part of one project, it is combining trailers from the 3 shorts I am working on, which were filmed 2 with 1 camera and 1 with the other cam. How can I set up a project in CS3 to use and display them all in the same video properly? Thanks :)

A key data point's missing. What format will your output project be? Whatever it is, use that preset. If it's 1080, upscale the 720 footage to fit. If it's 720, downscale the 1080 footage to conform it to the projects size. Not tough to do.

What do you mean by "upscale"? Just up the scale? Is there a known percentage to do so? Or should it fit visually?

*off topic*
I was just up in Conway yesterday, used to stay in N. Conway for summer vacations when I was a kid, beautiful area.

Just try... We cannot give a relevant answer without knowing your project settings. I would try to avoid upscaling, downscale your 1080 footage to 720 instead.

I don`t know the project settings either thats the problem, I am looking for how to set the project up best to handle it.

Another thought, can a DVD in Encore do the same thing? Play a video file that is 1080 then play another file that is 720? Would it display them properly and fill the screen?

Another thought, can a DVD in Encore do the same thing? Play a video file that is 1080 then play another file that is 720? Would it display them properly and fill the screen?

DVD is similar to the T Ford. It can play everything, just so long as it is within the DVD specs, meaning 720x480 NTSC resolution. No way to use 1080 or 720 material. It needs downrezzing first.

So, make a widescreen SD project and tick "Always scale to fit" in Preferences. This will take care of everything.