High-End Linux Hosts?

[ncjbhd]

My company's done shared hosting with our web site thus far. (I've gathered that the best of the best in shared hosting include Steadfast, DowntownHost, HostGator, Lunar Pages, and WebzPro. Any to add to the list, feel free!)

We're now thinking about moving to higher end hosting, i.e. a dedicated or managed server. So my questions are:

- Who are the biggest names and best quality Linux hosts in this category? That is, if those I mentioned above are "bargain" hosts, who are the "high end" hosts?

- What is the difference between a "virtual private server," a dedicated server, and a managed server? Ideally we'd like to still have a hosting package where security is taken care of and there's a lot of customer support to fix problems, but with our own dedicated resources.