Virtualization is what you are looking for. This can be done with local storage if you are going to consolidate to a single server. If you need redundancy then you will want two physical machines and shared storage. Depending on your virtualization solution this can be either SAN or NAS (if the NAS supports it). Personally I recommend SAN over NAS as the latency over fibre channel is much lower than over TCP/IP.
You can use VMware’s vCenter, Cirtix’s Xen or Microsoft’s Hyper-V solutions. VMware and Microsoft together hold over 90-95+% of the market so those will be the most supported solutions.