Can CD-R writers create DVDs

No. DVD uses a smaller wavelength of laser to make smaller pits in tracks that are closer together. The DVD laser must also focus more tightly and at a different level. In fact, a CD-R made on a CD-R writer may not be readable by a DVD-ROM drive (see 2.4.3). It's unlikely there will be "upgrades" to convert CD-R drives to DVD-R, since this would cost more than purchasing a new DVD-R drive.