Vegas is a non-destructive editing system. When you import clips into the timeline, you are inserting references to the portions of the files you are using, the original files are not harmed in any way. Now, if for some reason you only want to have a file of your “selected” clips, then render the project out as an avi file, you will then have a file of just the selected portions of the original footage (plus any changes you made to it, i.e. color correction, transitions…).
John Gordon
johngordon@cox.net