Each virtual or dedicated server has its own Os and works independently from the hosting machines of other customers. Updating the Operating system is often ignored, but doing that might have lots of benefits for your sites. The most important reason to use the most up-to-date version is that patches are usually released to fix security holes in the Operating System code, so if you do not install the updates, you risk people with malicious intentions to exploit these holes and to get access to your content. Operating system updates are also released for improved efficiency of the system in general and for far better compatibility with the hardware on the market, which can immediately influence the performance of your internet sites. If the efficiency and the security of your scripts is the reason to update them, you may also discover that their most recent versions require an updated Os to be able to operate properly, so keeping the OS up-to-date is always wise.