Graphics Problems Powerbook G4

I have strange graphics issues on my PowerBook G4. I'm worried the graphics card is dying. See image here

Since about Christmas I have had strange vertical lines appear. The are not in all windows and appear mainly in menus.

Since tonight I now have black boxes appearing around menu bars, windows, buttons and the like. It is only when they are active or focused.

Any suggestions or even confirming that my beloved PB is doomed are gratefully received.

Actually I put in a new HD in Jan, as the last one died.

I reinstalled the OS but copied over the library and user folders from backup - could I have copied over a corrupted file too?

(clutching at straws here)

Thanks for all the suggestions everyone.

On Saturday things got really bad with everything taking a yellow sheen and looking very noisy. So it looks like I'm looking at a new computer. One computer in almost seven years is pretty good going. I don't think I would have got that kind of life from a Windows laptop.

I was sorting some data out later that day and suddenly it returned to the state in the screenshot above. I have backed up and reinstalled anyway, but it didn't go back to a normal condition. Worth trying though.

Hopefully I can keep it limping on for a month or so until the new MacBook Pros are out, or even into the summer for OS X Lion.