Corel Draw is not professional lsoftware my friend. if u want to do imposition professionally try KODAK PREPS. i have been using this software. very goood and much professional.
CutePDF Professional. We've been using it for a couple of years and does everything we need for our digital press. Once created, settings are stored so you can impose within seconds for regularly used sizes. They do a free trial, but the paid for version is only $49.95. Best money we ever spent - really no need to spend hundreds when this does it all.