If you don't have Heart of Winter installed you need patch v1.06
If you install Heart of Winter the latest patch is the Trials of the Luremaster expanion.
This threads explains the patches:
http://www.ironworksforum.com/forum/...ad.php?t=98579
This is where you can download them:
http://www.sorcerers.net/Games/IWD/index_misc.php