Thanks for your quick reply. Although I've just realised I've got precompiled binaries in front of me and not stuff requiring compiling, your reply was not in vain - I've been meaning to find out...
I am running a Virtual Apache Server on a Linux system and am trying to install NetPBM from http://sourceforge.net/project/showfiles.php?group_id=7130&release_id=31626 for some GNU PHP software...