OK, this just seems absolutely stupid. WHY can't 10.4 Software Update provide updates for 10.5 clients? Seriously. You'd think that it could use ARD somehow and push out the updates regardless of client version. Just stick all the damn updates in a folder and push them out. It doesn't have a problem when sending Windows Updates. ARGH!
Does anyone know of a trick to force 10.4 Server to pass out 10.5 updates?