Multi monitors, a History
Macs get the leg up
Multiple displays have probably been around for decades when you consider the old client/server model of computing. You old timers may remember using those old VT100 "dumb terminals" hooked up to a large main computer. In reality, this is much more complex than a simple multiple monitor setup but it's still sort of the same idea. But what about consumer equipment? At the consumer level, the only place you could go to get multiple monitors was Apple. Macs supported multiple monitor/multiple video card setups for many, many years before PCs did (only recently with Windows 98). This is probably one of the reasons that graphic artists preferred Macs over PCs. Of anyone, they could appreciate the value of having a second display.
That's NOT the cool A/V Mac
The A/V equipped Macs (those with S-video out) were actually really cool machines to work with, especially when doing presentations. Not only could you clone the monitor image to a larger TV, but you could use the TV as an extension of the desktop for more area. I still remember using this setup for my days working at a Cal computer center giving software tutorials. It rocked! The setup worked great, and made me appreciate Macintosh a little bit more (despite the fact that our PowerPCs crashed 3x as often as our Dell PCs).
So what about PCs?
Back when Windows 98 was released, people were mostly hyped that it would natively support USB equipment. Lost in the excitement was the news that Win98 would finally support multiple displays on PCs. This was still somewhat of an obscure topic - who would want to pay for two video cards and deal with the hassles of configuring both to use dual monitors? Even if you did have the money for an extra video card, and the know-how to configure such a system, lots of people aren't willing to give up a PCI slot for it. The graphic artists were perfectly happy with their Macs, which supported dual monitors for years and ran their precious Photoshop a smidge faster anyway. Maybe if someone put two monitor outputs on a single cardů