Looking at the wrong costs

I'll admit that I like my Mac a lot. I read about it online, I got one for my folks, and I'm going to bring one into our office. A while ago there was this musing in techworld about corporate IT opening up to Macs. Among the cited barriers to adoption are needs for serial ports, scsi,tape drives and floppys, also known as legacy features that maintains compatiblity with older equipment.

It seems to me 1) that Corp. IT is looking at the wrong costs, the sunk costs; and 2)that they haven't learned all the lessons there were to be learned regarding necessary reduncancy and diversity. In age of spyware, viruses and trojans, it seems clear that having a mixed shop of Wintel & Macs are a good defense, especially if Macs have far fewer known issues.

Furthermore, when I entered the job market I used my dual profieciency as a strength, IT should do the same. If Macs 10 years out face more problems, and linux is more stable, then an IT shop should be able to respond, that seems like good business to me.