Go to this page:
http://egsc.usgs.gov/isb/pubs/factsheets/fs14899.htmlThe NED will be delivered in the Spatial Data Transfer Standard (SDTS) raster profile. The spatially referenced metadata will be delivered in SDTS topological vector profile. Other formats may also be supported. An Internet browse of NED shaded-relief imagery with vector reference information will be provided as an aid to ordering. A customer can identify the requested area graphically through the Internet browser. That area of interest will be extracted from the NED and from the spatially referenced metadata and formatted for delivery. The data will be available to download from the Internet using file transfer protocol or on standard distribution media. As more information on the NED becomes available, it will be accessible through the Internet at gisdata.usgs.gov/ned.
I do not think this metadata is yet available in SDTS so one will not be able to build a surface from the NED product...at this time.
One would still want to get the DEM file...
Further in that page also states:
A. ArcGrid is an Arc/Info proprietary format. Some other software packages can read the ArcGrid format. Customers who specify ArcGrid will be delivered a workspace. The workspace is not tarred or gzipped.
Testing seems to suggest MAP does NOT support this format.