It is important to quickly patch corporate and home systems as three "proof of concept" exploits have been quickly developed following the April 12th security updates from Microsoft.

http://isc.sans.org/diary.php?date=2005-04-13

MS05-016 - Windows Shell Vulnerability
http://www.milw0rm.com/id.php?id=938
http://www.securityfocus.com/bid/13132/exploit/

MS05-017 - Message Queueing Vulnerability
https://www.immunitysec.com/pipermail/dailydave/2005-April/001719.html

MS05-020: DHTML Proof of Concept Exploit Developed
http://msmvps.com/harrywaldron/archive/2005/04/13/41970.aspx