This is somewhat a continuation from my discussion on the thread "Do you use (or want to use) desktop Linux in your SMB?". Just a quick reminder, I'm "IT Director" for a small e-commerce company (in reality I'm the sole IT person, but my position is an important one in the company's goals) that's running a mishmash of Microsoft technology.

Recently, senior management has discussed trying to cut costs and improve efficiency. Before, I was only toying with the idea of using Linux and open-source technologies as a pipe dream, something that I would fantasize about doing, but without any serious consideration. After this discussion though, and pricing out what updating our licenses and software would cost from Microsoft (around $30,000, spread over three years, so roughly $10,000 per year), I'm now starting to really give thought to a Linux migration.

However, I have some concerns first, and I'm hoping some of the knowledgable Linux and SMB experts can offer me some advice:

1) When choosing a Linux distro, should I consider paid support? I dabble in Linux and UNIX commands, but I'm nowhere near as up to speed on them as I am with Microsoft. My home computer is dual-booted with Ubuntu and Windows XP, and I like Ubuntu, but for a business environment should I look at commercial providers, e.g. Novell or Red Hat for the servers? I know that Novell has a "Small Business suite" for SuSE, which would cost us roughly $1,000 a year (I believe it's around $500 for a 5-user license, so we'd need two). Red Hat, I'm not sure of what they offer but most of the pricing I saw was nearly as much as Microsoft. And, of course, Ubuntu is 100% free. For myself, I have no issue using the free version, but is the paid support worth it for an actual business?

2) Is there some sort of Linux equivalent to Active Directory? Not Samba, I mean a way to manage users, computers, create groups, push out software updates, and the like from a single point of administration? For server's we're going to need at least two, possibly three (Network/DNS server, Database server, Web server. Probably will go with all three since current server, which is several years old, can more than likely run Linux and so doesn't need to be replaced). At first, the clients will probably keep Windows XP (albeit move from Office to OpenOffice, and Internet Explorer to Firefox), so Samba probably need to be utilized for network and file services via the Linux server, but what about an all-Linux network? Again, I'm aware of Novell's suite including some sort of one-stop administration, but not of any others.

3) Our company has a standing contract with a CPA to keep our books; we don't have one as fulltime staff. This CPA uses Quickbooks (surprise, surprise) and remotes in to the President's XP computer. I know that remoting can be done via VNC in Linux, but does Quickbooks support Linux? I've read conflicting things on whether or not Quickbooks will run on Linux, but I suppose in a pinch I could run it via WINE? This is a big factor, although I'm not in a hurry to upgrade all the desktops to Linux, they could feasibly stay as XP with Linux servers and still cut costs on avoiding MS client access license fees.

4) This question I'm not really sure if anyone knows the answer to, but I'll give it a shot: For a new deal we're planning, there's a DLL in C# and .NET - remember, our current server is Microsoft and runs IIS, so this isn't a problem. I know about the Mono project, but is it possible to use that C# DLL in a web application running on a Linux server, say a Java or PHP application? This might be a big factor as it's supposed to be a pretty big deal.

Anyways, thanks for bearing along with my questions. I'm really interested in investigating Linux and open-source solutions now.