The job of graphic design designers is one where they require powerful computers, because they have to deal with image editing software's and tool which require immense processing speed, storage and memory. Most design firms especially the ones dealing with corporate identity logos & designs use only Apple Macintosh computers. The reasons are obvious: Macs have better ability to handle the graphical tasks at hand when compared to P.C.'s. But the gap between a Mac & a P.C. has closed down a bit as of late. Most designers long for a stronger hardware design and intuitive interface. PC's have started matching some of these benchmarks set by Macintosh but still can't compete with its graphics based OS which handles multitasking fairly easily & competently. Also Mac's are lot more stable and are virus proof, well almost!
But graphic design designers need to think beyond hardware and software yardsticks before deciding on what they want to buy.
Cost: Mac computers cost a lot more when compared to a P.C. Also Personal Computers can be assembled at cheaper rates. So if you are starting a new business venture and money is an issue for your company then opting for a P.C. won't be a bad idea.
Esthetics: It's often an important criterion for many freelancers when they go shopping for computers. Macs are esthetically more attractive and are designed to look sleek whereas P.C's come in standardized box shapes which are often not very appealing.
Availability of Software's: If you own a small business then it doesn't matter what platform you work on & basically it's what you come out with that counts. If you are working from your home as a freelancer, then opting for PC would be a better idea since there are lot more things you can do with a PC other than graphic designing.
One can conclude by saying that, though both have its pros and cons, the choice is with the consumer but owning a Mac computers would provide you with superior quality, time and cost benefit over a long run.