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When it comes to the total cost of ownership, Macs can end up being far cheaper than PCs for businesses that use them.

Just ask IBM.

Big Blue released data on Wednesday showing that it saves anywhere from $265 to $535 over a four-year period for each employee who uses a Mac over a PC.

To understand how we are at a place where IBM even has such data, you have to know that IBM no longer makes Windows PCs. It is also Apple’s primary partner in selling devices into large business.

IBM is actually Apple’s largest corporate customer, with 90,000 Macs deployed and an expectation that it will top 100,000 by the end of the year.

The company, which began letting workers choose Macs or PCs last year, says it has found PCs drive twice as many support calls as Macs and that IBMers are now “overwhelmingly” opting for Macs: 73 percent of IBM employees say they want their next computer to be a Mac.

That’s the nicest thing one computer company has said to another since Apple welcomed IBM to the PC business more than 30 years ago. Seriously.