Blocking Attachments when sending email

AD RMS
Transport Rules
http://technet.microsoft.com/en-us/library/dd351127.aspx
http://msexchangeteam.com/archive/2009/05/11/451274.aspx

Configuring Exchange Server 2007 to Support Information Rights Management

http://www.simple-talk.com/sysadmin/exchange/configuring-exchange-server-2007-to-support-information-rights-management/

You can use AD RMS to help prevent sensitive information, such as financial reports, product specifications, customer data, and confidential messages, from intentionally or accidentally being misused

http://technet.microsoft.com/en-us/library/bb123950%28EXCHG.80%29.aspx

Great info and thanks!  but what I am looking for is the user being able to select the individuals that get the attachment. In other words User X is sending an email to user A,B,C,D but only wants the attachment in this email to go to user B and D without having to create seperate email messages.

"Restrictions can now be applied in the core transport via Transports Rules. Connector restrictions as such are completely gone (since the concept of internal connectors is pretty much gone) and it's up to transport rules to enforce restrictions in Exchange 2007."
http://msexchangeteam.com/archive/2007/05/25/439547.aspx

The solutions may work but what I got out of the responses was there isnt anything in Outlook that the user can select to have attachments go to only select people in any particular email being sent. The other info given in the responses was great info just not relative to what I was asking specifically.