"or do i miss something in your question?"

I think you missed the part of the spaces and backslashes. To use your code, the input should be quoted (apostrophe) or escaped (backslashes):

$ cat script.pl
my $directory = shift @ARGV;
print $directory."\n";

$ perl script.pl 'c:\Documents and Settings\All Users'
c:\Documents and Settings\All Users

$ perl script.pl c:\\Documents\ and\ Settings\\All\ Users
c:\Documents and Settings\All Users
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Update Thanks to Corion I should add this disclaimer: "varying on the shell in use" ;)