I have been using Capture One tethered to Win Xp via 3.7x and it is super snapppy and I have yet to have the system or C1 crash. Honestly Only times I have had my PC's crash was when I had SSD installed or some software that wasn't compatible 100% I tried 6 with WinXp, it was super slow and not worth it. I switched to another system running Win7 64bit and all smooth, a little slower than the WinXp3.78 setup but doable.
I think most PC users have issues as they visit sites that wreek havoc on their systems. I have 8 PC's and 2 Mac G5. The Mac collect dust as my main SW is on the PC, and they are easily upgradable and interchangable FOR ME. The MAcs look good when a client sees it and feels confirmation that I am an artistic person. I think the bottom line is if you can afford a MAC Quad or 6 or * core system without a sweat, AND you don't like bothering with folders and how the files are ?managed", go with MAC. But if you are comfortable with Windows File manager and you know your way around systems, go PC. For C1, I wonder which is more stable, but I don't know, and have had only a couple glitches in C1V6.1 or .2? but it was quickly updated.