Safari 5.1.5 Update Improves 32-bit Stability
Following closely after the release of Safari 5.1.4, Apple released version 5.1.5 of its Web browser to address difficulties a number of users have had opening the program in 32-bit mode. Apple's latest hardware and software support has been for 64-bit code, but in order to support older plug-ins and for other compatibility reasons Apple includes a 32-bit binary for its Safari Web browser.