[Bryan Sanders] “I should have used ‘desktop editing'”
No, you’re using the correct editing mode. DV is a standard and only has one frame size (hence you are not allowed to change it) however, as you’ve discovered, there is a choice of pixel aspect ratio. One for 4:3 and one for 16:9.
Create a new DV project, selecting the DV Widescreen preset, then import your old project into the new project.
The old project will appear as a bin in the project panel. Open the bin until you see your sequence (probably called “sequence 1”) and double-click the sequence to open it in the timeline. (Do not drag the sequence into another sequence or you will be nesting.)
You will also find links to many free tutorials in the PremiereProPedia that will quickly show you how things are done in Premiere Pro.
Cheers
Eddie