Wasn't sure where to post this so sorry if this is the wrong section.

I'm creating a photo slide show in Vegas 9 Pro at 1440X1080 /24P. If I want to upload it to Vimeo how should I render it? Do I need to untick the "Stretch video to fill output frame size" box and de-interlace?

Well,

The question I have is if you are doing a slide show, why are you working in 1440x1080, and why do you have an interlaced project? Photos are not interlaced, and using square pixels (1920x1080) from the start would make things much simpler.

It's not interlaced. I got mixed apparently. So forget the de-interlacing question then. What about letterboxing? Should I leave that box unticked when I render or does it matter?

It's not interlaced. I got mixed apparently. So forget the de-interlacing question then. What about letterboxing? Should I leave that box unticked when I render or does it matter?

If things look correct in your preview window, there is no need to do anything else.