Like many readers of The Icon Bar, I started off computing with a BBC Micro. In 1991, I upgraded to an Acorn A3000, which was great because unlike Windows 3.0, you could print to a dot matrix printer and the printout would be just as it appeared on the screen. Then in 1994 I got a Risc PC, shortly after taking up the freelance role of Business Editor of Acorn User which I did for just over a year. Back then there was something about Acorn's RISC OS that made it a really good operating system. But the truth is that for many of us, using RISC OS has not been practical for some years. I loved the neatness of the ANT Internet Suite in 1996 but the internet world has moved on and despite important projects like Peter Naulls' Firefox port, I was a RISC OS user because I like the way how things just worked.
It seems to me that many of the reasons RISC OS users liked Acorn's operating system in the 1990s are reasons why people should consider choosing Mac OS X over Windows. What's more, unlike the RISC OS market these days, the volume in which Macs are selling make serious software development commercially practical: Apple, for example, sold 1.61m Macs last quarter alone, which means the Mac platform is extremely successful attracting the world's leading software developers like Adobe, Avid and MYOB. And of course Microsoft produces Office for the Mac.
I've used Windows extensively, from Windows 2 in 1989 right through to XP. But I chose Macs for where I work because we do not have an IT Department and I didn't want to spend my time fixing computers that have become infested with viruses and spyware, or just where Windows has messed up. We have very bright students who come for a few months to do research fellowships and the nice thing about Macs is that after the students stay with us, you get the computer back and you don't have to do anything with them. But with Windows machines, in the few months they have become slower, you find incomprehensible error messages on start up which you can't obviously remove, and you end up having to waste an hour reinstalling Windows.
The threat of viruses and spyware under Windows is well known. As the person who "knows about computers", I'm often asked by relatives and friends if I will have a look at their computers and one of the things I've concluded is that Windows machines and families with children really don't work well together. The computers quickly get infested. My Mac friends never ask for my help on spyware or viruses - they sometimes ask me what programs I would recommend.
Like RISC OS, the feel of the windowing system in Mac OS is quite 'loose'. In Windows, people tend to use the maximise feature and whatever application you are using fills up the whole screen (apart, normally, from the task bar). People tend to have only one window visible on the screen at any one time - you have Word open full screen, and then you switch to Access full screen and back to Word full screen. But when people use Macs, just as on RISC OS, it's much more common to have multiple overlapping windows. In a world of increasing monitor sizes, especially widescreen ones, I think the Mac approach is more sensible, and one that RISC OS users will find more satisfactory.
What you like in graphical user interfaces is often determined by what you are used to. What would ex-RISC OS users find most familiar? The Mac OS X Dock is more like the RISC OS iconbar than Windows' taskbar - it is application-centric rather than document-centric. In fact, I actually prefer the Mac Dock out of the three of them because it is very customisable - like a RISC OS iconbar on steroids. The Windows taskbar is designed to be document-based - each item on the taskbar represents a different loaded document. The problem is that if you have several programs and windows open, the taskbar quickly runs out of space (especially because each icon has text to its side) and the taskbar groups all of your Word or Excel documents into one icon, effectively switching to an application-centric approach. I also rather like Exposé on Mac OS which lets you press a button and it "instantly tiles all of your open windows, scales them down and neatly arranges them, so you can see what's in every single one". This is the sort of clever user interface design that was once the hallmark of RISC OS, making it easier to navigate programs and documents in Mac OS than under Windows.
RISC OS benefited significantly from its inherent elegance. The modular design of the operating system was good for its reliability and responsiveness. Today's Mac OS has very elegant approach under the bonnet because at its core it is a Unix-based operating system. Apple calls this Unix base Darwin; it is based on FreeBSD. The result is that the Mac is more stable than Windows. It was Acorn's intention to bring pre-emptive multitasking, multithreading and real-time quality of service support (which prioritises programmes that are time-sensitive, like video-conferencing) to its next generation RISC OS, codenamed Galileo. Thanks to the Mac's Unix-based core, the Mac offers these features, making the OS very responsive.
For the RISC OS user looking for another platform, there may be good reasons to go for Windows. But it seems to me that the Mac generally offers a better match. The Mac's user-interface more like RISC OS than Windows: as ex-RISC OS user John Hoare wrote on this site "using it has become pretty much second nature to me, in a way that Windows never did".