Hi Marc, - I may have been wrong about your drive being SATA. According to LiteOn nomenclature, the SH-16A7[B]H[/B] should be a PATA (IDE) drive with LightScribe. So I think we can rule out SATA controller/driver problems.
About the Ritek DL’s, I don’t think you’ll find many people here recommending them. Again, no personal experience with DL, as I don’t use it. Before taking the plunge and buying a Pioneer for DL burning however, you could consider “crossflashing” the HP to more recent (and probably better) original LiteOn firmware. The A7 drives are hardware-compatible with newer A1 versions and the logical LiteOn model for crossflashing your drive would be the LH-20A1H (current firmware version LL0D). This is entirely at your own risk however and will require some familiarization with the flashing tools and procedures (everything can be found here in the LiteOn section).
For DL backups, you’ll find the consensus is to forget about Nero and use ImgBurn. I also prefer to rip my movies as one ISO file in stead of a VIDEO_TS folder. Standard procedure is indeed to rip the DVD to HDD first, then do a full or a main movie only backup to DL or SL discs. There’s multiple commercial softwares to do this, but the freeware route is ‘DVD Fab HD Decrypter’ for ripping to HDD and ImgBurn for burning to disc. In between you can Re-author with DVD Shrink, if you want to backup the main movie only to SL disc for example. If the original DVD doesn’t have one of the latest copy protections, you may also use DVD Shrink or DVD Decrypter -predecessor of ImgBurn- (also in combination with RipIt4Me for more recent titles) for the ripping process. DVD Fab HD Decrypter is the only ripper that’s being updated however (and therefor can handle everything).
As you can probably tell by now, it’s a bit of a learning process to backup DVD’s. And there’s multiple ways/programs to get a similar result, whereby different people will have different preferences. I’m sure with a bit of time and effort though, you can do it too.