Every virtual or dedicated hosting machine has its own Os and works separately from the hosting servers of other customers. Updating the OS is usually overlooked, but doing that might have lots of advantages for your websites. The most significant reason to use the most recent version is that patches are usually released to deal with security holes in the Operating System code, so if you don't install the updates, you risk individuals with destructive intentions to take advantage of these holes and to gain access to your content. Operating system updates are also released for improved functionality of the system overall and for far better compatibility with the hardware on the market, which could directly affect the performance of your websites. If the efficiency and the security of your scripts is the reason to update them, you may also find out that their most up-to-date versions require an updated Os in order to function properly, therefore keeping the OS up-to-date is always a good idea.