A tip: before you make the switch, browse your DVD queue. Use your browser’s Save command (Ctrl+S, or on the File menu or context menu) and save the page as HTML. This preserves the links, including pop-up tool tips, for each movie in your queue. You can use this file to see if these movies have been added to streaming after your DVD queue disappears.
Tip #2: email this file to yourself for even easier access.
None of this would be necessary if Netflix had the decency to roll your DVD queue over to “Saved” under streaming, so these movies could automatically appear as they come to streaming. I cannot imagine why Netflix didn’t think of this. They could still do this retroactively, because they keep the DVD queue for a year or more.