Software Update Not Working

[Sambouka]

having a problem with software update. every time i try to download a 
new update on my software i get the following error: "The update could 
not be verified and expanded correctly. Make sure you have permission 
to write to /tmp/501/TemporaryItems/com.apple.SoftwareUpdate, then try 
again."

Even after trying to fix permissions several times i was not able to 
fix it.

any ideas how to fix this issue?

Sam
-- 
OS 10.3.3
Tibook G4 867 MHz,
1GB RAM, 32MB Video,
60GB HD, 250GB External HD
30GB iPod
iChat: Sambouka
http://homepage.mac.com/sambouka