Returning from a long absence

What size windows 10 SSD should I get? I run FSX SE on a separate SSD but I think a lot of files end up on windows. Is 120 gb enough? 

In my opinion, No.

Get at least a 250GB SSD or if not a 500Gb SSD for Windows, all its associated utilities and as you said some of the flight sim add-ons will all occupy space there.I remember on my FSX rig, UT2 consuming Gb on my C drive and there was no way to point the files to somewhere other than your C  drive.

Windows also need some "breathing room" as well, so going with a 120GB is tight and will likely mean you will run out of room in the not too distant future.

This is just Windows core files without any other apps installed.

Space for System Files — Recommend 30GB – 50GB
Space for Program Files — About 30 GB
Space for Hibernation File — Recommend  8GB – 32GB
Space for Virtual Memory — Recommend 12GB – 40GB
Space for Temporary Files — About 10GB
10%-20% Free Space of C Drive

 

You will easily consume the 120GB unless you plan to be very frugal in what you install.

Make sure its a decent performing SSD. Having a good working OS drive is key to successful flight simming.

 

Thanks for your in depth reply. It's been a few years but I do remember having to shuffle files around to keep windows out of the red. 

I think 500 gb I'd good piece of mind. 

A 500 GB SSD is more than enough for Windows 10 and gives plenty of headroom for updates and maybe even transitioning to Windows 11.