Help w/ exec()!!

Using IIS5 on W2K Server, I can't get get the exec() or other similar commands to work. This is what I'm doing - exec( "dir/a-d/b $dir_name", $arFiles ) The array doesn't contain anything! I've tried it with cmd.exe before the command, but it just seems to get stuck in a loop! Can anyone tell me how to successfully use this command? Or if not, any other ideas on how to get the files inside a directory into an array? Thanks in Advance, Shawn Sellars