KEY POINTS:
Before I start, I'd like to say I've never tried this. I have, so far, never found a Windows app I needed badly enough to have to use Windows. (OK, I haven't exactly been looking, either.)
Nevertheless, plenty of people want to or need to run Windows on
their Macs (and not just gamers) and so let's look at the options as there have been a couple of significant updates recently.
What's so great about that? Well, you can run Windows on a Mac, but you can't run Mac OS X on a PC (without considerable effort anyway - although see below under EeePC).
Firstly, there's the Apple option - use the free Boot Camp software, built into OS 10 Leopard. For this you need a licensed (ie legal) version of Windows XP or Vista to install alongside Mac OS 10. Every Leopard OS puts an App called Boot Camp Assistant into the Utilities folder in your Applications folder.
You can print out an Installation and Setup Guide to refer to as you go, if you like, or absorb the process for Vista on this SimpleHelp site - or press the Continue button inside the utility to proceed.
Boot Camp creates a partition on your hard drive to install Windows into, and once that's achieved you just select which partition your computer will boot up into in the Startup Disk System Preference dialogue box in OS X.
Easier still is to select which OS to boot up into on the fly during start-up by holding down the Option key and then selecting your partition.
Parallels Workstation is a popular solution as you don't need to reboot your Mac to change systems. It likes at least 2GB RAM and you have to pay for it (about $125 - US$79.99) - but hey, you can download a trial.
Parallels is popular because allows you to use Windows, Linux, and any other operating system simultaneously with Mac OS X. Parallels Workstation uses a 'virtualisation engine' so each virtual machine can operate identically to a stand-alone computer. Each virtual machine works with its own processor, RAM, hard disk, floppy and CD or DVD drives, display, mouse, and keyboard.
Another option is VWWare's Fusion, which has just shipped in version 2. It costs the same as Parallels. Fusion is built for Mac users and the company claims it's the "easiest, most Mac-friendly way to run Windows on the Mac", they reckon.
In Fusion, Mac-first user interface means users get the features they expect: customisable tool bars, searchable Apple help, Boot Camp support and dock notification integration. In the so-called 'Unity view,' you can run Windows applications like Mac applications, quickly switching between running Mac and Windows applications.
You can minimise Windows applications to the Dock, and even store Windows applications in your Dock like Mac apps. Version 2 has improved the Unity view plus added multi-display support for virtual machines, improved the 3D graphics and has added easier-to-use 'shared' folders for moving documents between the Mac and guest OS.
Fusion also has a demo version.
Cider is a wrapper - it's not virtualisation software at all. Before Cider, a game would have to be recoded - in particular the extensive Windows graphics files had to all be converted into Apple graphics files.
But not with Cider - this just allows Windows games to be run on Intel Macs without any modifications to the original game source code at all. Cider loads a Windows program into memory on an Intel-Mac, and links it to an optimised version of the Win32 APIs.
Games are 'wrapped' with the Cider engine and simply run on Macs, making simultaneous dual-platform game releases a snap. You can't download Cider as a consumer, though - you just have to hope a game developer is using it.
Finally, though, someone at Wired has figured out how to install Mac OS X on an EeePC - apparently, part of the appeal of the diminutive and cheap EeePC netbook is its hackability: hackers have already figured out how to run just about everything on them.
This would violate Mac OS X's licensing agreement, which specifically states that use must be limited to Apple hardware - so I'm not going to give you the link. It's easy enough to find.
Oh yes - some people who work in both Windows and Mac environments like to get Microsoft Mac-compatible keyboards so all the familiar controls are there - most of these controls work for both systems anyway.