Im not quite sure how easy it would be to use a computer as a digital transport while using it to do other things. The main topic being discussed in this thread is that one would use an external DAC along with a computer as the transport (be it a Mac or a PC). If I were to go down this path and use a computer as the transport, I would want the computer to be an integrated part of the system. This means I would have the Mac Mini, or PC laptop, sitting on the stop shelf of an audio rack using a short, high quality digital cable to go from the computer to the DAC. I suppose you could have the computer located across the room on a desk, but then you would need a very long digital cable; this can get costly. I may have misinterpreted your meaning of a dedicated machine for streaming, but if I were to use my current laptop I certainly wouldnt format the drive and reinstall everything just to have a clean install of the OS for streaming music. However, I would not use the laptop for other things during times when it is streaming music to the DAC just because it would require a longer digital cable; shorter cables always yield better sound quality, so I would not consider that option. Without this longer cable, it would be inconvenient to use the laptop as its sitting on top of the audio rack. So in my setup, laptops wouldnt necessarily have to be dedicated, but a desktop system like a Mac Mini would be.
Rsbeck did make a good point on being connected to the Internet to get song names from the CDDB. I had not thought of this previously.
As for the chop-shop PCsyou dont have to go to the cheapest manufacturer to get a good deal on a PC. You mentioned Dell, which you implied has higher quality standards than the chop-shop manufacturers. From Dell.com you can get an entry-level Inspiron 1200 laptop for $549. This gives you a Celeron M 1.3 GHz processor, 256 MB RAM, a 14.1 inch screen, 30 gig hard drive, and a CD burnerperfectly suitable for streaming digital music. Granted, the Celeron processor is not the greatest, but I would compare this with the processor in the cheapest iBook availablea 1.2 GHz G4. The hard drive and RAM are the same at 30 GB and 256 MB, respectively, but the screen is a measly 12 inches. The price for this iBook is $999. So for almost double the price, you a get a much smaller screen, same amount of ram, same size hard disk, and a slightly faster processorand most importantly, the ability to run OS X. Is it worth it? Well thats up to the user. As for custom built PCs, theyre they only type Ive owned, except I built them myself. Luckily Ive never had any problems with the hardware. For that reason I dont think that custom built PCs are necessarily low quality; you just have to be careful where you shop, if you are looking for a too good to be true deal.
The PC will not suffer from all the faults mentioned in your previous post, as I already addressed those in my previous post. The only things you mentioned that hold any substance are the claims that OS X is more secure. I wouldnt necessarily consider Windows XP to be inferior to OS X either.
Windows XP does allow you to quit individual applications if they do freeze, very similar to the force quit function in OS X. This function of the OS has been very effective since Windows 2000, although this version of the OS was run mostly by businesses. Its quite possible that you were using Windows 98 or ME the last time you checked for this function. Both of those operating systems are laughable.
So my bottom line is that either platform will work flawlessly for the task mentioned in the initial post of this thread, and that is to send a digital stream to an external DAC for use in a hi quality stereo system. Jazzdax asked if a G5 would outperform a conventional transport/DAC setup. My purpose in posting my message was not to debate which platform is better for all tasks in general, but to state the fact that a PC will stream music as good as a Mac, and will cost less money. So there are two final scenarios: 1) the computer is not a dedicated part of the audio system, and 2) the system is a dedicated part of the audio system. In a dedicated setup, my opinion is that it would be impractical to spend more money on a Mac for the ability to run OS X when the computer will not even be used for other tasks. In a non-dedicated setup, a Mac could make more sense, if a user is willing to spend more money for the benefit of OS X (this includes lowered vulnerability to viruses, and a better user experience).