reading an ESRI grid into R

Hi I'm using the raster package to load a DEM from here:
http://www.cec.org/tools-and-resources/map-files/elevation-2007

The data appear to be stored as an ESRI grid (adf) and I have no experience with this format.

From what I can tell this format is similar to a shp file with different files storing different things pertaining to the grid.

I'm using the raster command (raster package) to read the w001001.adf file:

dem<-raster("./Elevation_GRID/NA_Elevation/data/NA_Elevation/na_elevation/w001001.adf")

The produces what looks like a raster with values. Is that all I need to do or should I be reading these data another way?
Thanks
Julie