If you mean that you're looking to get an un-managed dedicated server at Rackspace, then just so that you know... Rackspace.com only provides managed servers.
Im now with a managed hosting company and Im looking for have a dedicated server (rackspace or other) for resell my packages.
Un-managed would mean that they won't help you with any software problems, they won't install any additional server software for you. They will only manage the network, and their own data center... what you do on your server is not their problem (as long as you're not breaking their terms and conditions). Even though you will have CPanel or Plesk control panel installed, these control panels only allow you to perform tasks via an online interface. But sometimes, these control panels don't work as they should and you'll find clients complaining about something not working, that's why you need someone to manage the server for you and to solve these technical problems. Someone managing the server would also install any other server programs that you want.
I want you help in what mean un-managed with a dedicated server with some control panel like cpanel/plesk, what else I need to managed on this server ? I need to install more programs ?
I hope this has helped you, your message was slightly confusing due to the english, but I think I understood most of it .
Former Systems Administrator