Apple today posted important updates for Mac OS X Leopard, and Mac OS X Server — both version 10.5.1. Also available is iMac Graphics Firmware Update 1.0. Apple says: “Mac OS X 10.5.1 Update includes general operating system fixes that enhance the stability, compatibility and security of your Mac; Mac OS X Server 10.5.1 Update includes general operating system fixes that enhance the stability, compatibility and security of your server; and iMac Graphics Firmware Update 1.0 updates the graphics firmware on the ATI Radeon HD 2600 Pro to improve system stability. The new updates are available from Apple’s Web site and via its Software Update preference pane.