Mac is not really oriented towards a residential market, they interest companies that need high performance computers for apps like Photoshop, Video Editing, etc... Since PowerPCs can get pretty beefed up (dual CPUs, 16GB RAM, etc...) they are quite fast and good for what they do. The home-user Macs are meant IMO for people who want more a more affordable solution to the super-speed and super-expensive counterparts. This would be useful if you worked at a place that used Macs and wanted to make sure everything you did could be compatible to other Macs. I wouldn't think of really ever using a Mac for general home use.
Also, I think Apple is in trouble since the main reason why they were able to beat PCs in video/image production is because it is a native 64bit OS and can handle MUCH more information than 32bit. Now that windows is moving to the 64bit world, Apple might have some stiff competition.