This is rapidly becoming a viable question once more. Macs were definitely faltering there for a while, but have picked up in popularity recently.

I have no intention of  fomenting or engaging in a partisan debate. I have experimented with many OSes, and they all have good sides and bad sides. Following is a list of the ones I consider most significant on the Mac vs. Windows front.

Before making any sort of hardware decision, you need to assess your requirements as a software developer. It is generally true that Macs are stronger than PCs in the arena of multimedia support. However PCs can be cheaper to purchase initially, and may be cheaper to upgrade as needed. Minimum RAM is 32 Mb for either platform, assuming you are not using the box as a network server as well. (If you are you should have at least 96 Mb.) 48 or more is really recommended. In either case, partition the machine's drive and set aside at least 200 Mb for system files, another 500 or so for applications, two times the amount of installed ram for virtual memory storage (if you have 48 Mb RAM, make a 96 Mb partition for VM storage), and the balance for your documents. This keeps areas which are constantly being changed from fragmenting other areas, and in my experience improves system stability tremendously.

Beware of Mac clones; they might not work properly at all. Contrarily, many PC clones are not particularly good ideas either, as they cannot use industry-standard cards and other hardware for upgrading system components. (A good idea -- if you have the technical aplomb -- is to get the individual components yourself and build your own PC. That's how I do it, and I've had precisely zero problems upgrading anything -- even on the motherboard level -- for years.)

Any multimedia PC will have to have a 16-bit or better sound card and should be able to display at least 800 by 600 pixels at minimum 8-bit color depth.

For Mac the display resolution issues are the same; however modern Macs have good sound support included.

Other caveats include the fact that some versions of Director do not appear to be compatible with G3 Macs; however, some versions of Director are not compatible with 32-bit Windows (95, NT).

What OS version you end up with is something else to consider. MacOS7.6 can have severe out-of-memory problems, even if you have, say, 96 Mb of RAM; most of these problems can be settled by using a control panel which fixes the machine's System heap. Newer machines will have MacOS8, which seems to have eliminated this problem.

On the Windows side, 95 is common. This makes many assume that it's good. A preferable system, however, would be NT Workstation, which costs only about US$30 more than Windows 95, but is considerably more robust, secure, stable, and networkable. (Note that's Workstation, not Server.)

A Mac system on which you can do effective multimedia work will probably run you about US$3500. A similar PC with the equivalent hardware add-ins will run you about the same. If the costs are equal, then, one might wonder why Mac is competitive, given the larger user base on the PC side. I can think of three immediate reasons:
 

Additionally, many US schools are using Macs. If you want to make a program that can be sold to schools, you'd better factor in Macintosh support. (In my experience it's not uncommon at all to find exclusively-Mac schools; of the user base I support -- some 1000 sites -- approximately 90% of them are Macintosh-only, the balance being Windows or mixed Mac/Win.)

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