Blank media is most definitely not all the same. The skipping problem you're describing is a classic symptom of poor media, or a poor match for your burner, possibly both.
We recommend Verbatim brand 16x media as a generally safe bet for blank disks. You can find them at Best Buy, or online. Taiyo Yuden 8x +R found at rima.com or supermediastore.com are also good. Sony can be an acceptable alternative, depending on the make and model burner you have.
We don't recommend burning modern 16x media at very slow speeds. If you have a new desktop burner (not a laptop burner in other words) you should try burning at half the rated speed of your HP disks....8x. For the Verbatim, try at 8x or 12x for best results. The firmware in modern drives just aren't optimized for slow speed burns.
What are you ripping the dvds with? The two most recommended programs are DVDFab and AnyDVD since they are still being updated. There is even a free decryption/ripping section of DVDFab, called DVDFab HD Decrypter. It will continue to work even after the free trial for the main section of DVDFab expires.