One of the benchmarks important to gauge performance of file servers and NAS devices is SPECsfs97_R1 set up by the Standard Performance Evaluation Corporation (SPEC).  This is a non-profit benchmarking organization and this specific benchmark has been created to establish network file system (NFS) performance.  Because of the nature of the organization and the fact that vendors have to submit the results for auditing, this benchmark has become de-facto standard for comparing performance between different devices.  As a matter of fact, there are end-users that rely on this benchmark to gauge overall performance of a file serving device even if this benchmark clearly only addresses NFS performance and not CIFS.  There is no equivalent organization as far as CIFS performance is concerned.  A popular benchmark for CIFS is called NetBench but there are no independent organizations that post CIFS benchmarks for end users to compare.  Hopefully, this will be rectify as CIFS performance is often more critical as many end users traffic is comprised primarily of CIFS based files. 
Microsoft and HP have worked with the Standard Performance Evaluation Corporation (SPEC) to establish NFS performance benchmarks for HP ProLiant DL585 G2 Storage Server running Microsoft Windows Unified Data Storage Server (WUDSS) 2003 Enterprise x64 Edition. The submission illustrates that HP hardware solutions with WUDSS will deliver equivalent or better single node NFS performance than other, typically more costly commercial network attached storage solutions.  For more details please see:
While I was at SNW last week, I was approached by a blogger working for a competitor of Microsoft in the NAS space to tell me how they have “taken notice” of the new NFS performance Microsoft can deliver with HP.  When you look at the SPEC SFS IOPs/$ that HP can deliver with Windows Unified Storage Server, I believe that a whole lot more folks will take notice.
Claude Lorenson