The 10.4.1 Update delivers overall improved reliability for Mac OS X v10.4 and is recommended for all users. 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
- Widgets: Address Book, Flight Tracker, Phone Book, and World Clock
- Creating and burning disk images using Disk Utility
- Compatibility with third party applications and devices

For detailed information on this Update, please visit this website: http://www.info.apple.com/kbnum/n301517