1. I had AC running on a Windows i5 machine with 4 GB in a peer to peer network and it worked fine.
2. Now I have SBS2011 standard server and I do not notice a whole lot of improvement in speed.
3. But remote access to multiple computers from a second office location has become a lot better.
So, if you have one office, stick with a Windows 7 64 bit P2P network, lot less complexity. But if you need remote access then go the route of SBS2011. For remote access, nothing works as fast as Windows SBS2011 remote work space - lot faster than LogMeIn, JumpDesktop, and even Windows remote access on port 3389.