Having a dedicated computer for audio is by far and away the best option. Set it up with what you need and no more, get it stable, image the drive, keep it off line and don't muck with it until and unless
the system needs to be rebuilt - then use that image. A heavily used system will probably need to be wiped and rebuilt every 6-12 months to keep it clean and running smoothly.
Constantly adding new plugins, OS and DAW software updates is asking for trouble. Attempting to stay on the bleeding edge of technology and features won't do you any favours in terms of maintaining a stable, reliable system. As tempting as new functions and tools are, if your system works fine as it is and meets all your current requirements, leave it be. "If it ain't broke, don't fix it."
Obviously not everyone can afford two computers, but be realistic as to your needs. You can make real music with surprisingly little computing horsepower.
I have an old
PowerMac G4/466MHz system running a Digi001 PCI interface, running ProToolsLE 5.2.3 on MacOS9.1 and PTLE6.1 on MacOSX 10.3.8. I put it together about 5-6 years ago, it was already unsupported hardware back then and well "out of date". The Mac itself cost a mere AU$60, with a few extra bucks to max out the RAM and put in a second IDE hard drive. The interface and card cost AU$250 back then - you can pick up one for about half that these days (just make sure you get the breakout box, cable and PCI card).
That's an 18 in/18 out system with MIDI I/O and 2 mic pres for well under AU$500, that'll record 18 simultaneous
tracks and playback up to 32 at 24 bit/44.1KHz off a single 7200 rpm drive. More than enough to record and mix a live band, multi-mic'd drums, the works.
Yes, there are limitations. It won't handle a heap of VSTis nor can I run 50 convolution reverbs either. MacOS9 RTAS plugins are hard to come by, and console surfaces need to be of a similar
vintage... though they're similarly cheap on eBay et. al. I'm currently considering getting a Mackie HUI, which now cost a fraction of their
original RRP due to Avid dropping support years ago.
Those sorts of limitations mightn't suit everyone - EDM/techno/electronic artists particularly - but with that system I've tracked and mixed a number of rock/blues live shows and rehearsals with nary an issue. It's easily been the most rock solid DAW configuration I've ever owned, and I've certainly spent a lot more time and money chasing my arse on newer systems. I'll never sell it.
It's easy to forget but no one was complaining about the quality of the music they were producing with the then state of the art gear back in 1999 or 2002. You can pick up rigs like this for very little... old ProTools TDM systems are now dirt cheap. If you can get past the desire to have elastic audio, flex time and 2000 plugins, there are some really good, affordable and reliable options out there.
Just some food for thought.
Cheers, Ben.