The replacement cdrom 3 is labeled Small business server 2003 Premium [but  not to worry - it's the same bits needed for Standard]

It looks like this -- [click on picture to enlarge]


You can also tell that it's the new disk by looking at the back inside ring of the cdrom .

Your original CD will have X10-03482, x09-73382, or x10-03888 on the inside ring.  The replacement cdrom has x10-30773 [trust me.... get a magnifying's there]



An easier way is to put the cdrom in the disk drive, click on explorer.... the SBS folder will be dated December 1, 2003