I have a Windows Server 2008 R2 box with multiple NICs (only one of which is currently in use). I have VMware Server installed on this box running a VM. I'd like to dedicate one of my free NICs on the host specifically for use of the VM, rather than use a NAT or bridged connection. Is this possible? If so, how do I go about setting it up?
You have to use some form of bridging, you can't present the NIC natively to the VM, VMware just doesn't allow that on any of their hosted Hypervisors (Server, Workstation & Fusion). There are some interesting developments with ESX\ESXi 4 with VMDirectPath IO and SR-IOV enabled hardware that allow some creative things to be done with Virtualization aware hardware - like map NICs directly to VM's for example - it may take a while for that to trickle down to the Server product and it will still require SR-IOV compatible hardware and support for this sort of pass through from the Host OS.
That said a custom Bridged Network will do what you seem to want (dedicate a NIC for VM traffic), although there will be some virtualization overhead which may be why you want to avoid it. To set it up use the Virtual Network Editor to create custom Bridged Networks for any of the unused customizable virtual networks (VMnet2 to VMnet7). Open the editor via the Edit->Virtual Network Settings menu then select the "Host Virtual Networks" tab, select your unassigned adapter and configure it as a Bridged network. Then connect the vNIC in your VM's settings to that Virtual Network. As far as worrying about the virtualization overhead (if you are) then that isn't something that is really going to make a huge difference unless you are massively stressing the network in that VM.