The 10.4.1 Update delivers overall improved reliability for Mac OS X v10.4 and is highly recommended.
It includes improvements for:
– file sharing using AFP and SMB/CIFS network file services
– using DHCP in wireless networks
– user login when accessing LDAP and Active Directory servers
– core graphics including updated ATI and NVIDIA graphics drivers
– synchronization with .Mac
– Address Book, iCal, Font Book, Mail, and Preview applications
– Dashboard widgets: Address Book, Flight Tracker, Phone Book, and World Clock
– creating and burning disk images using Disk Utility and System Image Utility (Remove)
– compatibility with third party applications and devices
For detailed information on this Update, please visit this website.