Gregory,
You have the highest resolution version of Natural Earth 1 that is on the Natural Earth Data website and which registers well with the vector drainage and coastline data. The higher resolution version of Natural Earth 1 on my other website does not register well with vectors, mostly because the vectors derive from old WDB2 sources, which are a bit suspect in terms of spatial accuracy, and were further tweaked to fit snugly with the lower resolution Natural Earth rasters. So the upshot is that higher resolution raster data will fit pretty well other more accurate vectors but not the vectors on our site.
I do not have experience with QGIS or GRASS and can’t offer you any advice.
Tom
Tom,
I just got back to having internet access and read your response from a couple weeks ago. Thanks for the tip. I’ll try using hydrology layers from elsewhere and see how they line up with the higher resolution raster from your other web site.
Cheers,
Gregory