Does this sound reasonable?
Yes, but that motherboard certainly supports USB keyboards. I would certainly go that way instead of PS/2 if possible. You might also consider a wireless keyboard.
Since PS/2 is really an obsolete I/O interface, does your keyboard maker even provide a W10 driver for it?
BTW, Windows Defender plays really well with Malwarebytes Premium without hogging resources or causing conflicts. That's what I am doing on 3 systems here. In your Malwarebytes menu, under Settings > Application > Windows Action Center, tick the button for "
Never register Malwarebytes in the Windows Action Center". This step will stop Windows Defender from disabling itself when Malwarebytes is detected.
Don't let anyone tell you Windows Defender is not capable of protecting you. Those people are most likely just Microsoft haters. While Microsoft does not code WD to score well in simulated lab tests (because they don't need the advertising fodder), do note Windows Defender keeps getting better and better and even bested many fan favorites in
AV-Test's latest round of tests in the critical category of "Protection" (click in the Protection column title to sort). When run with Windows 10, it beat out the likes of Panda, Norton, Trend Micro, VIPRE, Avira, BullGuard, ESET and others!
While Comodo is a nice firewall, the Windows Firewall is nothing to sneeze at either - and very light on resources too.
I am not suggesting you change from your current setup. I am just saying don't let rumors and falsehoods stop you from using Windows 10 WD and WF.