#1 No virus/spyware worries. #2 One vendor solution (OS/HW) no fingerpointing. #3 Powerful Unix operating system, so you can run and compile custom software. #4 Lots of powerful Unix tools. #5 Trading software runs on it fast. #6 No AV needed which means no I/O overhead. #7 Lots of trader friendly features such as Spaces,Expose,etc.. and you can customize lots of keyboard functions. #8 Workstation class hardware (Mac Pro + Apple widescreens) with ECC memory, Server class hardware to insure high reliability and security of data in memory from soft corruption. #9 The OS gets out of your way and lets you do your work fast with no bloatware or overhead like you do with Vista etc.. #10 Powerful built in backup, Time machine which always insure you have a copy on a second drive. #11 easy to swap drives, tool less case, rock solid operating system. #12 OpenCL and GCD is gonna open up even more power for advanced modeling. Just a few reasons why we swapped out to 8 mac pro workstations in 2006.