Advice on what to do with new 2008 R2 Server

[MachoManRS]

At our company we currently run one windows 2008 server. It has the following roles installed:

active directory domain services
dhcp server
dns server
file services

From our users point of view, we log into the domain from our workstations and have some folders we use for file sharing. We also use this box to serve a very old foxpro database ERP program. This is everything that I'm aware of that this machine does. We are updating to a new ERP program that will use MS SQL 2008 R2. In the process we've gotten a more powerful windows server 2008 r2 box. We went from an older dual core xeon and 2 GB of ram to a nice quad core with 8 GB of ram. My question is this, what is the ideal way to have our servers setup? We do still need to have access to the old foxpro database and program on the old server.

Should I just transition all of these roles to the new machine and then use the old machine just to host the foxpro erp program?
Or should I just join the new machine to our domain and load it up with MSSQL and soley use it for the new ERP software?
Or perhaps some mixture of the two, where I maybe just do ERP and file sharing on the new one?

I know this is going to depend a bit on the resource requirements ERP software, but the minimum specs for this software are even somewhat below what our old server has. From what I understand, the new server is overkill because we're only really looking at maybe an average of 4 transactions per second, probably lower. I think they just wanted a new server because they didn't want to have the old serving running both ERP programs, so they just picked out a new server that was around the same price they paid for the older one several years ago. You might consider in your advice (which I really appreciate!) that easier could be better, because I have very limited knowledge of windows server. I used to administrate some unix and novell servers years ago, but I've since changed my skillset and was recently given this task to complete, which I will do. I have a feeling that we have more hardware power than we need, so a smooth transition might be more important than squeezing every last drop of performance out of these servers.

Thank you very much for your help!

[strawberry]

Ideally each one of those services should be on more than one machine.

[MachoManRS]

Thanks for your reponse. Are you suggesting I use the option to "Add new domain controller to existing domain" and just run all of these services on both machines?

[timzim]

I'd shift the userfiles, foxpro and new erp/sql all to the new machine and leave the old one solely as a domain controller. Makes life a whole lot easier.

[Michael]

I'm not sure about your Foxpro database as this isn't something I have come across. Your new server should be promoted to a DC and you can also take advantage of the up-to-date features of 2008 R2. Everything should be transferred and your existing server could be used as a backup/file/print server.

If Windows Server isn't your cup of tea however, I would probably recommend you get someone in to do it for you.

[3s-gtech]

100% leave the old one as a DC/DNS server, don't take those roles off it as having a fallback is rather handy!

[MachoManRS]

Well thank you everyone for all of your answers. It seems that everyone has a different idea, which tells me any configuration will probably work OK. I'm leaning toward adding this server as a new DC in the existing domain and running the same services on both computers. I do like the idea of just putting both ERP programs and user files on the new ones and just leaving the old one as the DC, but running it on both seems better for redundancy. In addition, I'll use a scheduled robocopy to backup the file shares from one server to another. In this way, if one server goes down users will still get assigned IP's, still be be able to log on to our domain, access their file shares, and access either the new ERP or the old one.

I will proceed in this manner unless someone has a good reason for me not to do it this way, or I have misunderstood and it can't be done this way.

Thanks!