Spend the money on a decent server, with a server operating system, and you wont have any issues. It doesnt hurt with AC to also have a Gigabit network and if you have clients that are wireless (upgrade to wireless-n).
Absolutely true. We're running a Xeon E5410 (that's a quad core) @ 2.3 GHz with 8GB memory and dual 1TB 7200RPM drives in RAID 1. So in terms of hardware we're sufficient for what we're doing. Why we're running Windows 7 Pro on it? I have no idea, I inherited it that way, and so far we haven't had the budget or any meaningful reason to upgrade to Windows SBS. We don't run a wireless network because we don't have the need for it and it's one more piece to secure. (Wireless router default security is still a joke without isolating the network and using a VPN tunnel, IMHO).
Thanks again for all the suggestions! You guys are all super helpful and I really appreciate it![/quote]
Personally speaking, I wouldn't want to run SBS on the same server as AC. SBS has Windows Update Server, Exchange, SharePoint, etc. I think your just going to slow things down even more. I typically tell the Doctors I work for to just get Server 2008 R2. It's worked out really well for them (although I wish SQL Standard came with it).
Your "Server" seems very decent, an E5410 is pretty new. What are the specs of the workstations?