You may not really need a bit of software to do this, as this information is all stored by SQL, so it might be worth having a look at the SYSUSERS table.
Try having a look in the BOL, or maybe try just looking at the contents of that table and see if it helps.
If you know specifically what information you need to show in the report its probably worth posting that; someone here may already have written a query to do that which they may be prepared to post up for you to use.
Fee.
"The question should be, is it worth trying to do, not can it be done"