Best rendering output for 720px X 480px Sony Vegas Pro 12 I'm pretty new to video editing so please excuse if my question is rather entry level.

I have a bunch of archival films that were converted MPEG-2 at 720px by 480px. I'm required to put a watermark on them (which I've already figured out) and then upload them to youtube.

My question is, given the size (720X480) and non-HD quality of my archival film what would be the optimal settings to render in for Sony Vegas Pro? Or what would be the optimal format to render to given the above and it's end purpose being to get the best quality to Youtube? 

Any help is much appreciated
Not sure if you are asking about rendering to edit, or rendering for output to Youtube...

Whilst Editing pretty much whatever your system is setup up for will be fine, most likely Mpeg-2 or DVCPROHD will get you by...

But if you are referring to uploading to youtube, your best bet will be H264 since that is what Youtube will convert it to anyway.

Here is a little bit more reading you can do on Youtube Video formats...
http://www.ifunia.com/youtube-column/best-youtube-video-format.html