I doubt Apple still carries thwm but you can call Apple with the Serial# handy & see..
How to find the serial number of your Apple hardware product...
http://support.apple.com/kb/HT1349
10.3 isn't really worth much these days.
Tiger Requirements...
To use Mac OS X 10.4 Tiger, your Macintosh needs:
* A PowerPC G3, G4, or G5 processor
* Built-in FireWire
* At least 256 MB of RAM (I recommend 1GB minimum)
* DVD drive (DVD-ROM), Combo (CD-RW/DVD-ROM) or SuperDrive (DVD-R) for installation
* At least 3 GB of free disk space; 4 GB if you install the XCode 2 Developer Tools (I recommend 20GB minimum)
http://support.apple.com/kb/HT1514
http://www.ebay.com/sch/i.html?_nkw=mac+os+x+tiger+retail+10.4
See Tom's, (Texas Mac Man), great info on where/how to find/get Tiger...
https://discussions.apple.com/thread/3089008?answerId=15305521022#15305521022#15305521
old: http://discussions.apple.com/thread.jspa?messageID=9755670�
Or Ali Brown's great info on where/how to find/get Tiger...
http://discussions.apple.com/thread.jspa?messageID=10381710#10381710
Or join my site & ask...
http://x704.net/bbs/