I hate to tell you this, you might not have dead pixels, what you're seeing may be "normal" for this camera.
I don't know much about the G7, but the Rebel XTi (400d) also exhibits a white spot phenomenon, especially at higher ISO's. In some forums I've read, the consensus seems to be that this is due to jamming too many pixels on the same size chip as previous models, which requires more aggressive noise reduction, which creates the dots. Some people have been using either the Dust & Scratches or Despeckle filters in Photoshop with good results; see:http://forums.dpreview.com/forums/read.asp...essage=20902650
Turning down the in camera sharpening has also been suggested as a solution; again, not familiar with the G7, so I don't know if this is an option for you