GDAL Error - .grd not recognised as a supported file

Hi all,
I'm trying to work with the "ETOPO1 Global Relief Model", downloaded 
from http://www.ngdc.noaa.gov/mgg/global/global.html .
I chose the netCDF format option, which from the readme should be most 
appropriate for GDAL users.
Snip from discussions - http://n2.nabble.com/flip-raster-td1886005.html
"
I've posted new versions of ETOPO1 that GDAL can read properly (north is 
north) on the ETOPO1 web page 
(http://www.ngdc.noaa.gov/mgg/global/global.html), along with an 
explanatory readme file (in each netcdf folder). I've also created and 
posted geotiff versions of ETOPO1. Please let me know if any more 
problems are encountered.
Thanks,
Barry Eakins
barry.eakins at noaa.gov
ETOPO1 1 Arc-Minute Global Relief Model
http://www.ngdc.noaa.gov/mgg/global/global.html
"
However it looks like rgdal can't read the file. Or am I doing something 
wrong?
Can anyone suggest the simplest way to get this data into R (I'm 
avoiding the geotif due to bad internet and possible memory limitations 
on my PC)?
Many thanks,
Darren


input_file<-c("C:/Users/Darren/Documents/ecology and 
conservation/SP/data_gis/RASTEr/ETOPO1_Ice_g_gdal.grd")
file.exists(input_file)
[1] TRUE

library(gdal)
readGDAL(input_file)

Error in .local(.Object, ...) :
        GDAL Error 4: `C:/Users/Darren/Documents/ecology and 
conservation/SP/data_gis/RASTEr/ETOPO1_Ice_g_gdal.grd' not recognised as 
a supported file format.

R version 2.9.0 (2009-04-17)
i386-pc-mingw32

locale:
LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United 
Kingdom.1252;LC_MONETARY=English_United 
Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base    

other attached packages:
[1] rgdal_0.6-8 sp_0.9-36 

loaded via a namespace (and not attached):
[1] grid_2.9.0      lattice_0.17-22 tools_2.9.0