I strongly do NOT recommend to use Mac OS X Leopard in a productive environment!
The initial release 10.5 got launched on October 26, 2007. It contained a number of serious bugs which should have been addressed in the first upgrade. On November 15th Apple released the first major upgrade 10.5.1. Most people believe all serious bugs are squashed by now and start to use Leopard in productive environments. I would rather wait for 10.5.2 or even 10.5.3!
Here you’ll find an extensive article about the massive data loss bug in Leopard by Tom Karpik.
His tests are based on Leopard 10.5 and I didn’t find any information about this bug still persisting in 10.5.1. But I was pretty shocked about what happened to me last night…