I've been a PC user for the last several years. For sign related stuff, Windows and Intel/AMD-based PCs are perfectly fine. It's also arguably best to do web development and web design on Windows-based systems since they display color differently and use different system fonts.
However, I am seriously considering the purchase of a dual processor Mac for my next home desktop system. I have a new Dell notebook and my aging Dell desktop PC still works fine for most purposes. The addition of a Mac would be good for my freelance print-based work and also for video and motion graphics work I would like to pursue. I can do a lot of those things on a PC.
The only problem with buying a Mac is high cost. The CPU tower alone with some decent options (like at least 2GB of RAM) easily goes over $3000 or $4000. Apple's monitors are arguably too expensive. Dell has a new 24" widescreen monitor $500 less than Apple's Studio Cinema Display and with better reviews. New software could nearly double the cost, certainly with adding Adobe's CS2 package and Apple's Production Suite. Overall, I'm looking at a cost over $6000 to get a Mac system configured the way I need it.
Obviously I need to see enough of an advantage from a business standpoint (not the silly Mac versus PC performance arguments) to justify the purchase. What kind of business opportunities can I expect to gain from having a computer running Final Cut Pro? It's kind of a scary thing. It really gets scary if you want to consider adding a lot of video production hardware (cameras, lighting, sound, etc.) into the mix.
There are trends of businesses adding video displays into POP settings, buying message centers capable of displaying graphics and video, but without the knowledge needed to produce the content and do it well. Some of the trends in the economy put some of this possible growth into question. In the meantime, I'm just saving money and trying to make sense out of the situation.