The iMac’s CPU is integrated into the 17 or 20 inch LCD display and all Mac peripherals are either FireWire (IEE1394) or USB 2.0 (USB 2.0 is as fast as FireWire 400). Dell’s XPS 400 solution cost about the same as the top model iMac (there are 2 models) when similarly configured.
The Dell E1705 laptop has a larger screen (17in) than the MacBook Pro but I expect Apple will soon offer 17 inch PowerBooks with Core Duo processors. Other than screen size the Dell and Apple laptop offerings are about the same price when configured similarly.
Of course all Mac’s come with video editing software, Apple’s Front Row software (equivalent to Media Centre PC), Garage Band music recording and editing software, or a remote control. The Dells have none of this.
I bought a FireWire enclosure (includes a USD and FireWire hub) added a 160GB drive and hooked it up to my Mac mini. I put my video, photos, music on the FireWire drive and the performance is awesome. Because OS X has I can play my music and photos on my TiVo (which is connected to my home theatre amp) over the home wireless connection. Both my wife and I can sync up our iPods quickly to the mac mini and TiVo has a deal with Apple to provide support for downloading TiVo show directly to the iPod Video.
I think I will be investing more into Apple than into Microsoft in the coming years. Of course, Apple’s solutions are proprietary, just like Microsoft’s, so I will still maintain a Linux OS in my home.