I was going to move on to a discussion of virtualizing Windows on the Mac, but before I get to that I think it may be worth a short discussion around some of the Windows-related issues you'll need to deal with regardless of which method you choose. Indeed, this conversation about running Windows on the Mac is going to be a bit more involved than I originally thought.
The first issue you're going to have to deal with is ... Windows. That is, while you'd have a hard time finding a PC that doesn't come with Windows 8.1 these days, if you get a Mac, you need to actually buy Windows. This is something that the vast majority of Windows users are actually not familiar with.
To be clear, obtaining Windows isn't just about cost—though it can be expensive, as you'll soon see. It's also about choice. Unnecessary choice.
Where Mac OS X just comes in a single version—one that even includes a free upgrade to Mac OS X Server if you need that for some reason—there are multiple versions of Windows. Not just multiple "product editions." Multiple versions. No, not like Windows 7, 8 and 8.1. Multiple ways to buy essentially the same thing.
The simplest way to say this is that Microsoft basically sells four retail-ish versions of Windows 8.1: Windows 8.1 "Core", Windows 8.1 "Core" System Builder, Windows 8.1 Pro, and Windows 8.1 Pro System Builder. The prices (at Amazon, your results can vary) break down like so:
So there are a number things to think about here. There's the "Core" version of Windows 8.1 vs. Pro. And then the System Builder versions vs. the retail versions.
To decide between Windows 8.1 "Core" and Windows 8.1 Pro, check out Microsoft's helpful page (which also includes Windows 8.1 Enterprise). Unless you have very specific needs for work, Windows 8.1 "Core" should be just fine.
Regarding System Builder vs. retail packaging, check my article Windows 8.1 OEM Media, which described the System Builder version. Basically, with System Builder you can save a lot of money, but you only get one disc (in 64-bit) and very minimal packaging, which shouldn't matter. There used to be some weirdness around whether System Builder was legally OK, but that's not the case anymore: You can legally choose the System Builder option.
And maybe you should. Except for one potential issue. I'm not sure yet if this is true on the Mac, but it was true on the Windows side that if you were better off using the 32-bit versions of Windows in a virtual machine (VM), since that system consumes fewer resources and runs faster (virtualized) than do 64-bit versions. Point being, if you intend to run Windows on a Mac-based virtualization solution like Parallels (which I'm using) or VMWare Fusion, you may be better off with 32-bit. (This is a topic worth exploring further.)
Long story short, if I'm spending my own money, I get the System Builder version of Windows 8.1 "Core," which is $90 at Amazon.
Once you get past that somewhat convoluted decision, you can install Windows in a VM (Parallels, Fusion) or in a dual-boot scenario using Boot Camp, which is included with Mac OS X. I'll be writing about both of these methods soon, but here's another issue: When you install Windows 8.1 either way, it will activate automatically. Which means, if you choose a virtualization route first and then decide later to delete that and try Boot Camp (or vice versa), you may run into problems activating Windows the second time because it will appear to the OS as if you just installed it on two different PCs.
To get around this limitation, you may want to experiment with a free trial version of Windows 8.1. This is actually the Enterprise edition, not "Core" or Pro, but it will provide you with a way to see how Windows will really run on your Mac without burning through a product activation key. It's good for 90 days and you can choose between (or both) 32-bit and 64-bit versions.