I believe you're looking for SyncToy
www.microsoft.com/downloads/details.aspx?FamilyID=c26efa36-98e0-4ee9-a7c5-98d0592d8c52&DisplayLang=en

Give it a source and destination folder and it'll keep the content synchronized between the two, I haven't played with it in a while but the mirror setting sounds like what you're after.

It looks like they're up to version 2.0 whereas I last tried 1.4 which you had to manually schedule the sync with a scheduled task but even that isn't difficult.
(bill, Wed 14 Oct 2009, 19:46, 2 replies, latest was 16 years ago)

I'll give it a go, cheers
the idea being that I can save work to My Documents (or whatever and I click save, it saves it there. but then the software copies it to the folder on the other drive automatically, so in essence it's like it's been saved to two locations at once,
( sandettie light vessel automatic New Twitter - @bollocksreally, Wed 14 Oct 2009, 20:23, Reply)

That's how it works
I've just setup similar myself as a test, I'd guess of the three sync settings you'd want to use 'Contribute' so deletions aren't replicated across.

You will need to setup a schedule to run it but that's detailed quite well in the help menu.

Edit: That's assuming you want to use it as a backup against accidental deletions, If you just want to protect against drive failure then the default sync will delete from D: when you delete from C:
(bill, Wed 14 Oct 2009, 23:15, Reply)

ooOOoOOOoo handy.
Do you know anything about setting up Subversion? I'ld love that shit on my server.
( G/PP 💩💩💩💩💩&#128, Wed 14 Oct 2009, 21:01, Reply)

Sorry fella, Not a fucking clue.
I'm much weaker on the FOSS stuff then on MS.

It shouldn't be too hard to setup though from what little I do know.
(bill, Wed 14 Oct 2009, 23:30, Reply)