I was going to suggest replacing the DVR109 with a similar newer internal 5.25 drive, but the DVR109 is IDE, not SATA, so finding anything current is probably not possible. Being IDE, it’s probably a very old computer. I’ve been the whole upgrade route with Pioneer drives from IDE to SATA to external enclosure firewire and USB2 and they all worked fine with Wavelab 6, up to and including the current Pioneer USB Blu-Ray burners I think. But any of the LG and similar should be fine too. Or you could find a refurbished Pioneer IDE burner on NewEgg or TigerDirect or Ebay that would probably work fine for a long time, if you’re willing to replace the internal DVR109.
If the internal USB is USB1 on the computer (you should be able to tell from Device Manager or Computer Properties), an inexpensive USB2 PCI card from Belkin has always worked fine for me, for using any external USB burner.
fwiw, I’ve even used IDE to SATA internal conversion adapters without problem, if you want to get a newer internal SATA burner.