When you order a dedicated server, it usually comes naked with its operating system of your choice (usually a Linux flavour or Windows Server edition), but without any system administrator support beyond what ISPs usually call 24/7 remote hands support.
If anything goes wrong with your machine, support will typically only do what you tell them: reboot the machine, restart this or that service, read off the screen, etc. Unless you are a sysadmin, this is not going to help you much.
Ideally, you should go for the complete package, i.e. you make sure you get the hardware from a reliable ISP, you make sure that they have system administrator staff at hand who are able to dive into your needs and individual setup in order to be able to actually do something about the issues you might be facing. That often implies that your developers and your sysadmin staff must cooperate very closely. Your developers need to be aware of the capabilities and limitations of your machine, and your sysadmin(s) need/s to understand what your applications do, how they react to spikes, how many resources they are using on average, how subsets of applications (such as DB service, webservice, etc.) interact with each other, and so on.
Our advice: do not save on sysadmin money. 24/7 availability of a system administrator for your applications and server, someone who knows his way around your machine and applications, is an invaluable asset. It might add to your monthly cost, but if you want to be sure that you are not on your own when push comes to shove, having someone experienced to handle the problems for you is, in fact, a must.