Why It Works
Some service bureaus and printers remain resistant to supporting PC files. While the situation is likely to change with the influx of PC users requiring professional printing services, Mac users who must work extensively with commercial service providers and other Mac-based firms do have an advantage in terms of compatibility and overall acceptance. This could also translate to cost savings for the Mac user because service providers unaccustomed to PC files may charge more for their handling.
For very high-end work where precision color-matching is absolutely required, the Mac may continue to have an edge over PC hardware and software options.
In terms of cross-platform compatibility, Mac wins. Although there are programs that allow the PC to run Mac programs, at present, it generally works better the other way around so Mac users can often get the benefit of PC software without having a PC.
Why It Doesn't Work
PCs dominate the corporate and consumer world. Despite the Macs superiority in networking and cross-platform compatibility, there is still sometimes the need to run PC office suites, email programs, proprietary software, and even games that aren't possible on a Mac.
To get the speed, storage capacity, and graphics capabilities necessary for most professional level design work will push the cost of the Windows PC closer to the cost of a Macintosh of comparable capabilities. However, for those who already have money invested in a PC and are technically savvy, upgrading a PC can be more cost-effective than buying a new Mac.
Where it Stands
The old standby arguments for why only a Mac will do for serious design work are no longer valid. Either one will work. Where there are still key differences such as for high-end color work and trouble-free integration with other Mac-based operations, the user must decide how important that difference is to their own situation.
Emotion is still a big factor in the platform wars. Going with Apple and the Macintosh may be viewed as an act of rebellion against the norm of PC ownership or against the dominance of Microsoft. If it makes the user feel good, why not.

