Pacific Digital DVD-----S L O W

Got a Pacific Digital USB 2.0 External 16X DVD Burner for Christmas, since have used it to back up my movie collection, however, seems that no matter what settings I tweak the write speed does not change. To back up a movie generally takes about 1.5 hours, also I have tried several different software packages, DMA settings, memory re-allocation, hd de-frag, different media, nothing helps. I am currently using CloneDVD to do my back-ups. Does anyone have any help for my slow, tired, drive? The manufacturer’s web site does not have a recent firmware patch. All is running on a Pentium 4, 2.5 ghz, 80 gig machine…