As it turns out, some people in the lab are able to update certain apps, but not others and it is not consistent from computer to computer. For instance, while I was unable to update to 10.2.4 on several machines, another person downloaded the 10.2.4 update fine, but couldn't get the iMovie update. Someone else couldn't get the 10.2.4, iMovie, or the G4 firmware.
Bizarre.
kman