Here you can download the previous version (version 1) of the GADM database. This version is obsolete. Version 1 of GADM maps 226,439 administrative areas (or 167,176 if you count only the lowest level for each country). You can see them on these maps.
These are very large files. It is best to download by country. But if you really want the whole world: Download version 1.0 as shapefile or ESRI geodatabase (for ArcMap 9.2).
You can also download the global data for a specific level of sub-division:
Level 0 (country) --- shapefile --- geodatabase
Level 1 --- shapefile --- geodatabase
Level 2 --- shapefile --- geodatabase
And you can also download the countries transferred to a 30-arc-seconds global grid as ESRI grid
The coordinate reference system is latitude/longitude and theWGS84 datum.