You may find
http://cplay.sourceforge.net the best all around write-up of how to put together the best PC-based server, the theory behind sampling and especially jitter and why cPlay is claimed to be the best software to play your files, and these folks are not even shy to replace the Windows Explorer shell with their own... It appears that the attention to detail, especially in minimizing jitter all over the computer, is nothing short of fanatical.
Would be curious to see feedback from the tech savvy like JonFo.
Well, I agree with Jeff, the UI is pretty bad.
Also, while I know a PC can be turned into a pretty accurate playback platform (using digital outputs, not analog), but hassle factor is huge.
But if really looking to use a PC as your 'transport', you can consider using some really high-quality RME Hammerfall cards (~$500) as the output.
The Soolos uses this card internally.
The other way to get good quality playback is external firewire devices like those from M-audio. If looking to use analog outs, this is a great way to decouple from the electrically noisy PC environment.
For software, I tend to really like Foobar2000. It has excellent audio performance, fully supports ASIO and has a very high quality re-sampler.
But after a decade of screwing around with PC based playback, I've dumped it in favor of what I now consider the ideal playback platform:
Start with a collection of high-quality digital data ripped from whatever source with high-accuracy. Currently, i use dbPowerAmp rippers.
Use a preamp that has built in DLNA Digital Media Rendering (DMR) such as all the latest Denon's. this gives you a clock-synched chain between digital audio decoding and the entire preamp stream right into the DAC's. Zero jitter.
Use a laptop, touchscreen PC or tablet running a DLNA control point such as Twonky Media manager to selected and push playlists to the DMR, and you have a system about as good as as a Soolos in usability but with higher audio quality due to the clock-synch inside the DMR.
It's still not perfect from a usability standpoint, but it's the one area where there is a lot of effort going on to improve.