I just bought it off Craigslist last week and look like in top condition but how can I find out how old is this laptop?
I use Wikipedia. I start with the CPU, then narrow it down with the other specs.
http://en.wikipedia.org/wiki/Powerbook_G4
I hope yours is new enough to be an aluminum PB. The TiBooks wifi is weak.
Which model is it? You can check using System Profiler.menu>About this Mac, click on "More Info..."
Useful info would be the model identifier and CPU frequency.
PB G4s were made between 2001 and 2006.
Just copy serial number and paste it there: http://www.chipmunk.nl/klantenservice/applemodel.html
This site will tell you precisely how old your Mac is - manufacturing date is coded in serial.
Very interesting information I guess this is VERY OLD one