How to change SBS 2003 server into a Windows Standard 2003 Server

Hello Experts:

I am currently running a SBS 2003 Server and I would like to convert it to a Windows Standard 2003 Server.  Is this possible?  About a year ago, I seperated Exchange from the SBS and am running a seperate Excange 2007 server.  So email shouldn't be an issue in the changing from SBS 2003 to a standard server.  

Thanks for the help