I have a 2006 Kona Dew and I want to put drop handlebars on it. I've been told by one of the local bike shops that the only way to do this is to also install a new cassette, front and rear deraillers as the road-style shifters are not compatible with my rear derailller. I'm not convinced that this is necessary, because don't most cyclocross bikes have MTB deraillers and road-shifters?

Can I just swap in road-shifters to replace the MTB style that are currently on the bike and keep the rest of the components? I don't want to spend a fortune upgrading this realitively cheap bike.