The NEC 4571 (and 3551/4551) drives don't support LightScribe - they support a competing technology called LabelFlash.
In order to use LabelFlash you need special media (different from LightScribe) and AFAIK that media is not available in North America.
It's possible to use the NEC LabelFlash capable drives for making labels on the remaining free space on the data side of DVD media however, if you think that's interesting. This technology is called DiscT@2 and requires at least 900 MB available space on the DVD.
For me it doesn't make sense to have a LabelFlash capable drive when the media is not available in your region so I'd stick with the 4570 drives as they are, but that's just me.