Q: i have a pb 1 gig g4 ti wont update os

Your Powerbook will not upgrade past 10.5.8.  Is your data backed up?

Yes, because the only point in upgrading is the slightly better security of 10.5.8, and slightly better application compatibility.  Upgrading could reveal underlying issues you wouldn't otherwise see. If you are having issues besides know compatibility issues, I wouldn't upgrade.

10.5.8 can be found here:

http://support.apple.com/downloads/Mac_OS_X_10_5_8_Combo_Update

First identify which Powerbook G4 you have:

http://support.apple.com/kb/ht3065

Then compare these two pages to determine which Airport card you have:

http://support.apple.com/kb/HT1621

http://support.apple.com/kb/HT3024

If you don't have an extreme card internal compatibility, you'll want a WiFi ethernet bridge with 802.11g or better to maintain a secure connection, with your Powerbook hooked up via ethernet to that bridge.

WPA2 is not supported by Apple's original Airport card.