I use two PC's for a number of reasons:
1. I have two Hard disks, redundant. I have all files duplicated on both PC's.
2. I can run one PC independent of the other, with two Connections, to try out various FIxes and troubleshooting, and, for example, I can run Services.msc and try out various settings to solve the un-ending issues with Admin problems and so that Microsoft causes.
For example, the other day, after an Update, my Microsoft Admin credentials were reset so I could not even load a new program (Quickbooks) because of System errors from the Admin side. I solved this issue using the OTHER PC which was still working fine, as both PCs are identical and the other one was my Wife's old PC that she no longer needed as she bought a Tablet. So, I simply loaded up Quickbooks on the other PC and kept working and worried about the ADMIN issues for later.
As a blogger, it is great to have a companion PC running the dialogs, and the primary PC running charts)....and if one connection is lost, the other kicks in as I use two connections, one with a Cradlepoint and the other is a Smartphone)...and with concurrent connections, there are always interrupts.
I could list 20 good reasons why having two PCs with separate Hard disks, connections, is better than a single PC with Dual Monitors. I had such a setup one time and had a crash, and lost $$$$$ in five minutes in a live trade. I trade options and at closing on Fridays, the action is exciting and lucrative (I run Strangles, weekly, and it is great $$$).
So, for all those reasons and more, I personally prefer two PC's independently running on a 100% duty cycle.
DJ
p.s. I am quite surprised by your question, honestly. MWB works flawlessly, loads automatically and two PCs are better than one. I ran an MIS dept for a Silicon Valley Company and this is where I got some experiences with redundant databases which saved my Butt many times.