Just a quick one to share some options on virtualization on Mac.
VMware Fusion Pro
Although paid software, this is what I recommend going for, especially if you want to virtualize an ancient OS. Unlike some alternatives VMware provides drivers even for some ancient guest OS, so you can run for example Windows 98 SE just fine. It can also set up a Mac guest with a click of a button, using your Mac’s recovery partition as installer source. VMware seems to be more for professionals and enterprise customers, but now that I use VMware Fusion, I’m not going back. Oh, and, they provide full DirectX 10.1 support and graphics acceleration so you can play games in your Window VM for example.
VirtualBox is the free and open source software by Oracle. It’s great if you just want to install recent Windows or Linux real quick to run some software not available on Mac. The downside is that graphics acceleration isn’t really a thing yet, at least not for gaming. You also can’t run ancient OS as well, or at least not without a lot of fiddling around. Since it’s free, it’s great when you’re on a budget but then you should ask yourself why a Mac? ;)
I guess that one’s OK if you’re a complete n00b but still want to run Windows in a VM, even for some gaming. The downside is that, not only is it paid software, but also the fact that the standard edition limits RAM and CPU for each VM. The advantage is that a lot of things are simple “one click and things happen automagically”, which is ideal for n00bs.
This free app allows you to emulate DOS to run most DOS apps and games, for free! The advantage is that having an app is much smaller than a complete VM and system integration is better, as you can mount any directory with ease. But it does have a bit of a learning curve and it requires knowledge on how to use DOS and be familiar with terms like “mounting”. If you’re techy enough and just want to run a DOS application or game, try this one first!