Upgrading software using used discs

Hi fellow ebidders!.
I have a mac osx power pc G5 which runs on panther. I need to upgrade to "tiger" so that I can upgrade my browsers. I cannot afford to buy the Tiger software new as it is too expensive for me so I've been looking at used discs. I've never upgraded before and have heard stories about people buying used discs and then the discs not working and they lose their money. Can somebody please tell me if I buy a used version of Tiger would it still work if I just put the disc in and ran it? Also what should I be looking for , I've seen DVD's and CD software discs for sale and I'm not sure which are the actual software or whether they are info discs.
Many thanks for any advice, Tess

In general when you buy software you just buy the license to use it.
You are not allowed to re-sell it.

That is the rules, but I do not think they are fair.

Otherwise I can't help you as I'm a windows gal.

But there will be some Mac users out there who will be able to help you.

Thank you. I found a used upgrade and the seller gave me his phone number if I have any problems with the disc so hopefully I'll be alright.

On an Apple power pc you could use Yellow Dog Linux, then everything would be free and legal, no worries about whether there's a licence agreement tying your hands.

Um, actually there is a licence, and it does impose certain obligations on you, e.g. if you pass on Linux to someone else you have to give them the licence as well and you can't charge money for it, only a copying fee!