Performance for WSS2003 should be comparable to that of Windows Server 2003.
You can find benchmark information on the Microsoft website:

"LP" wrote in message
> Hi
> I am looking at replacing our current file servers (running W2K server /

adv server) with NAS devices running WSS2003. Are any performance results
available for WSS2003? What is the threshold of concurrent open files on
WSS2003 before a significant performance degradation occur? I found that on
W2K adv server the server performance takes a serious dip if the amount of
open files exceed 15'000.
> Thanks
> LP