OS upgrade question

OK this might sound completely stupid to some of you but I really am brand new to this and don't want to screw something up.

My friend gave me a powerbook G4 that has Mac OS X 10.2.8 for an OS. I would like to upgrade that OS to 10.4 ( I think that he said that 10.5 wouldn't work) I am wondering #1 can I do this upgrade, #2 I am thinking of buying a copy of 10.4 from ebay but I have no clue as to what I am looking for. Any suggestions?

I really hope this works I like this computer for what I want it to do basic web browsing, iPhoto, that sort of thing. It does have an airport card so I can use it at WiFi spots but sometimes pages don't load properly because I can't update my browser, my ipod won't sync because I can't update iTunes.
So that's a drag.

Thanks for any help
867 MHz
PowerPC G4
Ram 640 MB
Machine model PowerBook6,1 (version 3.3)

It will support Tiger but not Leopard. I think that you can get tiger discs on ebay but make sure that Its not an upgrade disc. You will have to do a complete re-install if you choose to upgrade.
Hope that i could have helped!

Thanks that is exactly what I needed.

If i was you i would just buy the upgrade disks and do a fresh install of your OS, that way everything will run smoother and you can get all the crap thats on your HD off i.e. cookies, caches and unused apps etc...

check this out http://cgi.ebay.com/Mac-OS-X-Tiger-10-4-11-Update-CD-disc_W0QQitemZ320340833309QQcmdZViewItemQQptZUS_Software?hash=item320340833309&_trksid=p3286.c0.m14&_trkparms=72%3A1234|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50