Couple of quick showstoppers with Windows Small Business Server 2003:

1. Upon installation, make positively sure you put in the Active Directory information in correctly. If you make a mistake, you are fucked. Reinstall the server. The only way.
2. Never delete or rename the MyBusiness Organizational Unit (OU) or make any changes inside of it. Doing so will fuck the server bad.

Those are two lessons I learned recently. Learn from my mistakes.