microsoft security updates

[#1]

Is it necessary to keep updating windows using security updates if you are using firefox.
I can see the need to keep programs updated but its the security updates I am curious about ?
I am running a firewall,virus checker,windows defender etc will this not cover it?

[#2]

Yes
I'm no security expert, but I would have thought that a number of these updates will apply to believed flaw in the operating system itself and so therefore beneficial to install.
Sure, some will be applicable to Microsoft hardware, but I reckon it's best to be safe than sorry.

[#3]

Yes you do need to keep your system updated with security updates. Many are not related to the browser but the OS and other applications / DLLs.
Firefox does nothing to protect against OS exploits and in some cases firefox will still be vulnerable if it uses a windows library/dll that has a security problem.

[#4]

Firefox is actually very suseptible to XSS attacks (like in its Password Manager).
It's always a good idea to patch your operating system with security patches, because without them it makes it much easier to gain access to your machine (prime example being the old lsass vulnerability, which still remains exploitable in many, many machines)

[#5]

Thanks for that !
I will keep security updates on.

[#6]

And if you don't want to use IE to update your M$ Windows, you can use http://windowsupdate.62nds.com/ instead whilst running  Firefox