Run Exchange Standard W2003 in SBS 2003 domain.

Hi, we have a customer SBS 2003 server with exchange on it and we want add new server to the SBS domain, Windows 2003 standard and Exchange on it, to bypass the limitation of SBS and then disable the Exchange from the SBS but make SBS still available for storage, dhcp, dns and PDC use. First, is it possible? Then what is the best way to do it? I have read lot of websites and text about, like heretechrepublic or msexchange.org but not excaly the situation we have. Most talk about 2000 SBS or get 2 new server then remove the SBS. He dont want buy the transition pack and just add new server with exchange. If someone can give me the way, it will be really helpful. Thank you.