Crash

Hard disks are built to tolerances that Apollo engineers could only dream of and are therefore more sensitive than most imagine. They get hot, cold and external drives get shaken about - which will eventually have a similar effect to doing the same to an etch-a-sketch. 2.5" drives seem to be more reliable in such circumstances, but you still have a disk than rotates faster than most car engines will ever go and heads that have to quickly zip back and forth over the surface without touching the disk. The long and the short, is that if you have an external disk, you're best to have it in an actively cooled housing and try not to move it. Something like the QNAP TS-412 in a seperate room would be ideal, although it's not portable.

Garf, I feel you've directed your funds in the wrong direction. In order to get the best out of your system you need to get some of these for your headphone cable: http://www.russandrews.com/product-Cable-elevators-4227.htm More importantly, without one of the following, you'll never hear the music the way God intended: http://www.stealthaudiocables.com/products/indra/indra.html It's expensive I know, but there's a cheaper option to improve your system: http://machinadynamica.com/machina60.htm

You can set the sound to go through either machine using remote desktop. That said, you'll end up with bit soup if you channel the sound into your laptop. Sound from your headless PC will be unaffected by your controlling it via remote desktop.

As a disclaimer, I should say that I work with PCs and are therefore rather biased, but have you considered an Atom based HTPC? They much more flexible than a laptop. I've got a Zotac http://www.amazon.com/Zotac-Dual-Core-Motherboard-Graphic-NM10-B/dp/B003D3KASS. It's cheap, has enough power to run Blu-ray seamlessly, has a coax digital out and if you wanted, you could plug a BlackGold TV tuner into it. I realise this is a audio site and not home theatre, but as you mentioned a receiver, I thought you may be interested. Strictly on the audio side, I have mine plugged into Audiolab Dac and then into a low to middling level stereo Naim set-up. I'm pretty happy with the result. To confuse you further, you could use three sets of discs; an SSD for the OS which would be silent, a dirt cheap NAS which you could put in a different room where it can make all the noise it wants and possibly a local cheap hard disk which only wakes up for recording or recording TV. The best thing about the set up is that you can get it up and running for very little money and add or change internal and external components as and when you like. It's a very tuneable solution. Lastly, don't be put off by the thought of nailing your own computer together. It really isn't complicated and there are some great guides about.