You have asked a rather wide open question as you haven't said what you would be expecting this server to do, but generally the answer is yes, there are several Linux based server packages available that will do pretty much anything that a SBS server will do, I use clarkconnect (
http://www.clarkconnect.com ) in several locations as servers on windows networks with great success .
Probably best to check the site for a full list of what it can do but asides from running the very occasional application that is server based and demands to be run from a windows based server I've found it to do everything you could want from a server.
It is worth baring in mind what VHG said that the restriction on needing XP pro is due to the home version of windows not being able to join a domain and if you where to setup a linux based server as a domain controller then you will still have this problem