ok, Im totally new to owning a mac. Ive had pc's since forever it seems like. A family member gave me a PowerPc G4 with Mac os X v10.1.5 theres around 500ram r something on it. thats all i know. Im having a hard time trying figue things out. On my Pc's i grew a fan of Fire Fox, but when i try and install it gives me can not mount image. ive searched though google for a couple hours and came up with and update that would sopose of ly "fix it" but when i downloaded and tryed to install it says can not be installed on this computer. Its the 10.2.8 combined upgrade. im sure theirs some updates that will help. I just need to download a better on thier because internet explore on my mac either crashs or wont load the page fully. i cant download Safari with it because it wont show the download buttom. any help will be greatly appreciated. If some one can lead me the in the right way that would be great.

PowerPC G4? No such model. It is tower or notebook? Maybe Power Mac G4?
You have system 10.1.5 you can't update it to 10.2.8 because you must have at last 10.2.0 to update. FireFox do not work with 10.1.5. Try to download system 10.4 (PPC) from here: click
If you have PC computer and Flash disk (fat32 formated) try to download torrent on pc then move it with flash to mac. Next burn first cd. I don't remember exactly how to burn in 10.1.5 but if you don't burn it right it will not boot. It may be a problem if you don't have cd writer:
1. Open the Disk Copy application (/Applications/Utilities).
2. From the Image menu, choose Burn Image.
3. Select the first image (Mac OS X Install Disc 1.dmg)
4. Click the Burn button.
5. When prompted, insert a blank CD-R disc.
6. Click the Burn button.

Do not use any other program to burn.
After burning restart from CD:
1. Insert CD in computer.
2. Turn computer off.
3. Press power button (turn computer on) and hold down C key on keyboard

If it startup from CD it means that you burn right bootable cd. Then just restart in normal system and burn next 3 cd. After that restart again from first CD and update or Clean install mac os x 10.4.