Classic British Flight Sim

I've mentioned elsewhere about mounting problems with my FSX.
My HD is now about 4 or 5 years old, and about 80% full.
I have a Netgear NAS duo, which is sometimes attached to the system, holding a couple of discs, originally purchased for backup. Windows tells me that Drive Z is 1.8 TB, don't know if that's both discs, or if it is only looking at the first one.
Because we often get pwer blips, the NAS shuts down, and needs 8 hours to re-sync with the internal drive before it can do another backup.
I have very limited knowledge in this area.

To run a completely fresh install of FSX:
Could I use one of those NAS drives? ....and if I did, does that mean no more backup facility?
Am I better off putting a SSD inside the box?
Should I get another "normal" internal drive?
Any better suggestions?

Mike,
If you are suffering power interrupts or 'brown outs' then the first thing I would suggest you do is buy yourself a back up un- interruptible power supply. Mine is an APC ES 700, which when fully charged says I have 24 minutes running time with the current equipment connected. It can also be set to auto shut down when power gets low. Its certainly saved my HDD's from crashing due to power glitches & power outages. Not necessarily cheap , mine cost about 100 Euros about 4 years ago. Batteries are replaceable, but over here the cost & postage cost are almost as much as buying a new one!
Thanks to my computer oriented son, I also have a Samsung SSD that carries my operating system only, with my various other HDD's & another smaller back up SSD
used for every day work. Apparently SSD's do not like being read/write to all the time & they die because of that. I also use lots of USB sticks for back up.
Hope that helps & good luck
Keith