If you just want the files, use the dirplu() /a-d option, it will only return the files.

Code:

$e = "%userprofile%\Mijn documenten" 
$mydocs = dirplus($e, "/s /a-d")
for each $file in $mydocs	
       $docfiles=$docfiles+GetFileSize($file)
next
? $docfiles + " used by My Documents