http://tinyurl.com/microsoft-foundationIndy makes some great points about closet space and using WIN7 and cost, etc. I hope I am not arguing with him. I am more trying to answer the actual question.
The question, if I understood it correctly, is "I am thinking of a server instead of a regular workstation and peer-to-peer setup. What would you recommend?" If the question were, "What would be the least amount of money to spend on a network and still get good functionality with AC, that would be a different answer.
The thread on the Foundation is an interesting one and gives the pros and cons of its use. I find it to be compelling.
Back to the question at hand. First, Indy makes very good recommendations on the physical space. I just want to make sure you don't obsess on the space requirements. Mine if two feet beside me. I wish I could find another place, but I can't. And, while I still remote into it all the time, there is nothing better than being directly in front of it. Of courses, I play with my server three times a day while others don't touch it for months.
OK, while a peer-to-peer setup with XP Pro (10 connections) or WIN7 (20 connections) is plenty (you could have 500GBs of space) 4 Gigs of RAM and a high-end processor, it is still not server software. Yes, a server OS would require CALs which are costly, but again that was the question so here is the answer.
Server computers with server OS are still more reliable, dependable and faster than workstations with WIN7. Do you need it? Probably not.
The analogy I would use is the following: If you work 20 miles from work in a warm climate with good roads, etc., do you need a Honda Civic or a BMW? Take your pick. They both will safely get you to and from work each day. They will both probably last 100,000 miles or more, and, given that you have speed limits, they both will likely perform about the same in what they need to do. It's just do you want to save money and get the Civic or do you want to spend more money and get the bells and whistles of the BMW?
Besides the fact that the server is going to outperform the workstation, it will have bells and whistles AND the platform to add more bells and whistles than the workstation. I think when people talk about servers, they look at the situation the same way they do backups.
When strategies for backups come up, they are always strategies based on the 100Mb compressed, encrypted little file made by AC backup. It is as if there is no billing data or scheduling data (if using another scheduler) or any other data on the computer. Just back it up to your thumb drive and take it home. We will talk more about that at the ACUC.
And, likewise, when we talk about networks and servers, etc., everyone talks about it as if the only thing that matters is AC. I will be fair here since I have brought it up twice. That was the question. What is the best server for AC? But, if I may have a little bit of liberty, if you are going to have to put together a network, and you are going to have to maintain that network, wouldn't it be more fun if the network were more fun? Wouldn't it be cool if the network were not only safer, more redundant and faster, but just all in all more fun. And, wouldn't it be cool if you could add things. (Man I wish I had another PCIx slot so I could add a DRAC card (Dell Remote Access Card). Those things are just way too cool.
So, what types of things am I talking about? I will show some at the ACUC. But, IF one decides to go with SBS 2003 or 2008 which comes with 5 CALs, you could do the following. First, you would have SharePoint. That is the company web that is so cool, words can't describe what it can do. Come to the ACUC. There is readily installed SQL Server Standard Edition if you use the premium editions. Different in each. There is Microsoft Exchange so you can host your own email and send Outlook email to users without violating HIPAA. AND...you are HIPAA compliant with email storage. I won't even get into security and group policies and Active Directory with its computers and users management. Tired of your MA changing her wallpaper to her cats and all of her grandchildren. Just one setting on the server. Want to change all the screen savers to one kind and have them pop up in 60 minutes, np. Should they auto lock. Same thing. Group policy.
Now, I am not saying that is worth the extra money. Just answering the question and giving some extra info as well.
But, I do see where Boondoc and Indy are coming from, and I think it is good to see the other side.