Some updates released in the past couple of months.

You may be unable to apply more updates at a certain point on a Windows Small Business Server 2003-based computer.
https://support.microsoft.com/?id=940276

An update to turn off default SNP features is available for Windows Server 2003-based and Small Business Server 2003-based computers (948496)
https://support.microsoft.com/kb/948496

The version of Small Business Server 2003 does not appear to be the R2 version after you install the R2 Technologies CD (931268)
https://support.microsoft.com/kb/931268

Error message occurs when you open a Microsoft Management Console (MMC) snap-in after installing Windows Server 2003 Service Pack 2 or Windows Small Business Server 2003 R2 Technologies: "MMC has detected an error in a snap-in" (947532)
https://support.microsoft.com/kb/947532

Software updates are not managed by Microsoft Windows Small Business Server 2003 Update Services after you install Microsoft Windows Server Update Services 3.0 Service Pack 1 (945985)
https://support.microsoft.com/kb/945985

You may experience network related problems after you install Windows Server 2003 SP2 or the Windows Server 2003 Scalable Networking Pack (949533)
https://support.microsoft.com/kb/949533