WE Branch Fanatic,
DVD uses a smaller wavelength of laser to allow smaller pits in tracks that are closer together then a CD. The DVD laser must also focus more tightly and at a different level. In fact, a disc made on a current CD-R writer may not be readable by a DVD-ROM drive. (DVD player or drive use two lasers at different wavelengths: one for reading DVDs and the other for reading CDs and CD-Rs.) It's unlikely there will be "upgrades" to convert CD-R drives to DVD-R, since this would probably cost more than purchasing a new DVD-R drive.
Take Care,
Richard