Been running Linux at home and at work since 1994. Does everything I need it to do, including web development, software development, typesetting, audio; you name it. The audio on my CD (see userpic; available on CD Baby) was entirely recorded, edited, and mastered on Linux.

There are a couple of fields where software on Linux is lacking; games and graphics, sadly, among them. And as for security and stability:

[steve 508] ssh -lroot gc
Last login: Tue Sep 18 07:40:58 2007 from 198.180.216.25
gc:~# uptime
 21:20:53 up 512 days,  2:00,  2 users,  load average: 0.00, 0.00, 0.00