Internet Mail
This is the desktop mail protection provider. If this is not a terminal server, you probably won't need to run this.
Outlook/Exchange
dtto.
MS SMTP 2000/2003
This provider is loaded on demand. That is, it will (should) become 'Active' as soon as a first SMTP message is delivered by Exchange.
Share Point 2003
You probably don't have SharePoint 2003 installed. It is not part of SBS2003 -- it is licensed separately as part of the Office 2003 suite, I believe.
Hope this helps,
Vlk