Currently I have a RAID setup thus if my windows PC hard drive crashes, I can still keep working. How ever if my power supply or motherboard crashes I cant do much.

Assuming if I buy an identical PC, how can keep my 2nd PC syncd with my primary PC.

Right now I do back up to an external drive but that will take few hours of restoring and their is a risk it may not work.

I used to work on stratus aftServer but thats an overkill for me. I am ok wiht few hours of downtime.