This is shown on the W page for the IBM Software Support Lifecycle. It also shows that support for WSAD 5.0 ended on April 30, 2006.
|Product||General Availability||Withdraw from support|
|WebSphere Studio Application Developer for Linux and Windows, V5.0||10 Jan 2003||30 Apr 2006|
|WebSphere Studio Application Developer for Linux and Windows, V5.1||29 Aug 2003||30 Sep 2006|
So, if you're still using WSAD 5.x, what should you do? Upgrade to RAD 6.0. RAD is the next release of WSAD. It can be used to develop apps for WAS 5.0 and 5.1--just like WSAD--as well as for WAS 6.0, and has newer features than WSAD.
See also: WAS 5.0 Support Ends in September.