Vegas will auto-recognize the media as being 24p in Vegas version 7c, regardless of what sort of timeline you create.
I've had two people email me with projects/media saying "24p looks weird."
In both cases, they had 60i timelines with 24p media in it. So, Vegas is re-inserting pulldown. Open the HDV 23.976 template, and you'll see smooth, correct 24p.

Frame output
 

Hello, shot project with a JVC HD100, 24p, Vegas 7, rendered, looks great.
Went in to tweak project, render, the whole frame is smaller. Not sure what changed but I think I might be 'rendering as' something different than original.
Should I not use 'widescreen' beccause it was shot natively 16:9? Or any other input. Everything seems to output the whole rectangle/frame smaller.
Thanks and happy new year.

nasty cuts from punches!
 

I've noticed that transitional cuts from punched in clips give me a horrid transition. It's almost as if I can see the image wipe from bottom to top of frame. It's an uncomfortable cut on the eye. Any ideas? I remember chatting with a Vision Mixer on a Studio production some time ago while he was timing the procamp on the mixer to cut between sources better. It's a similar effect. Surely it's nothing to do with that is it?

Piece shot in standard DV 25p.

Michael,

Did you "check" the "do not letterbox" option in the "Render As" dialog box?

Set the preview window background to white, play the file from the explorer tab, or put it on the timeline, and see if the "black bars" are there. If they are, put a check in the aforementioned option and render the original project again.

I assume you rendered in 720 X 480 widescreen. This also assumes your project properties settings are the same as the output settings.

Jamie