First, some background: 

I work for a small company that does IT. Recently I have become the "web developer" as a value added for the clients we support. The business had a guy who set up a web hosting company about a year ago (before i got here) also for a value added for our clients. It is configured with helm v4 and has 3 servers (all running windows 2003) in a co-location.

**The Problem:**
The guys who set up and maintained our web hosting portion of the company.. got up and left!! And.. me being the web developer have been put in charge :) YAY right.. NOT! I have no real experience maintaining this kinda thing so I am a little stuck. We host around 100 sites.. so we cant just cut this off. 

**The question:**
What do you guys suggest I do here. Where do I get started. I need to somehow get control of this. I dont like helm4, it sucks, there is no support etc. None of the users require control panel access really except for using the email. (we are using smartermail module).

**My Solution:**
I was thinking about restarting everything on my own accord. Using Linux or Windows, Apache, MySql..etc. I have another server box I can get started on to test and learn. Since the users dont use the control panel, I could manually create new domains when they come. If I do this, does anyone know any guides or faqs on how to get started on this. Obviously I need to learn about security and such as well.

ANY help would be appreciated!!