Apple's Mac Pro Audio Update 1.0 for early 2009 Mac Pro models comes only with terse release notes, stating that the update "reduces processor utilization during audio activities such as playing or recording music." More information regarding installation steps is available on Apple's Web site. The update is available via Software Update and the Apple Support Downloads page. (Free, 1.64 MB)
Option-Click AirPort Menu for Network Details
If you hold down the Option key while clicking the AirPort menu in Mac OS X 10.5 Leopard, you'll see not just the names of nearby Wi-Fi networks, but additional details about the selected network. Details include the MAC address of the network, the channel used by the base station, the signal strength (a negative number; the closer to zero it is, the stronger the signal), and the transmit rate in megabits per second showing actual network throughput. If you hover the cursor over the name of a network to which you're not connected, a little yellow pop-up shows the signal strength and type of encryption.