PowerBook G4 Problem (Jumbled Screen Images)

I have a 1.33 GHz PowerBook G4, 1.25 GB DDR SDRAM running 10.3.9. I upgraded to Leopard awhile back. Everything was running well for at least a year or more. But recently I am experiencing problems with jumbled screen images (funny wiggly lines in different places). I thought it might be the upgraded 1GB Kingston DDR SDRAM, but I removed it and still had the problem. It got so bad that I did a back up of the hard drive and started fresh with the restore CD going back to the original OSX. It worked fine for several months, but now the problem is back. I thought it might be a problem with the video card, but when it happens I would go to another program and then all is fine. Because of that someone told me it probably is not the video card, but a software conflict. Any help would be much appreciated. I took a screen shot of when it acts up.

It does look like a graphics card (chip) issue! ....intermittent, or application specific doesn't rule it out.
I would run an apple hardware test, but IMHO, looks like your graphics chip which is integrated into the logic board is on its last legs.

Thanks so much. I ran the hardware check and it gave an error when it checked the video card. My PowerBook had a good life span 6 years. I guess it is time for a new MacBook.