I seem to be late recognising this problem...
KB931784 first failed Apr 12 2007 (and repeatedly ever since).
KB926505 first failed Jun 08 2007 (and since)
For KB931784 I tried creating Downloads folder (on C

but the run command
eventually produced an error message saying wrong software version. Perhaps
this only works for Windows XP SP2? I have not tried any alternative update
methods for KB926505.
All other updates (too numerous to list have installed successfully):
Windows Server 2003 - last update Jun 13 2007 KB935839
Windows SBS 2003 - last update Dec 24 2006 KB921096
No updates (critical or otherwise) are showing on Windows Update.