problems after downloading update for 2.9.8

After I download the zip file, the installer extracts but does not go thru the set up process...Anybody know what the deal is?




Well When I double click on the installer icon it appears in the dock for a sec and then disappears. I am on a 400 mhz power mac G4 with Mac OS 10.1.5 and i have 1 gig of RAM.