I use Vegas 10, but I think these two versions are very much alike.
-Try Project -> Render As...
-By the drop down box that says "Template:", click the button that says "Custom..."
-In here, you can specify all of your video details such as resolution, framerate, pixel aspect ratio, and codec.
*Note, you can use options here which are entirely different from your project
properties. Make sure you're using the correct aspect ratio when you set your resolution, or it may come out skewed. You can set the project parameters in Project -> Properties. You will always get the best final outcome when the project properties match the output settings.
