The iMac G5 cannot run OS X Lion, it is not possible.
You have an Intel iMac, lat 2006.
I believe you are at the top of the OS range right now, Mountain Lion may not install on that machine
BTW, while it was handy in this case, it is not a good idea to post your serial number in a public forum.
I have an iMac g5 late 2006 with the following:
Processor 2 GHz Intel Core 2 Duo
Memory 4 GB 667 MHz DDR2 SDRAM
Graphics ATI Radeon X1600 128 MB
Serial Number *************
Software Mac OS X Lion 10.7.5 (11G63)
I was wondering if I could update it to mountain lion. I am afraid that i can't and buy the software. Help please.
Note: This post was edited by a forum moderator to remove exposed serial number on 05/28/2013 at 8:14 AM PT