You have to do your updates.
No matter what operating system your computer is running, you want it to be safe.
As I have been doing the preventive maintenance on our clients systems, I was struck by the fact that a couple of computers were still running Windows 2000.
As workstations, they still function, although slow, but they still require the same updates as all of the latest systems. Just because you have an old system, with an old operating system, does not mean it is not vunerable. In fact it is the weakest link in the chain.
Microsoft does an incredible job keeping up with updates, but only if you download them.
Please keep in mind, if you are on the Internet on a daily basis, you need the later operating system that is much more stable and safe and supported. And in a network environment the risk of infecting the other stations far outweighs the cost of upgrading.