Hi, I have a G4 MDD dual 1.42 ghz, and I would like to increase performance. There are 2 things that bother me : HD 1080p isn't that fun.... Doom 3 has periodic lag. What trick would make me able to play Doom 3 and lets say... watch downloaded videos from youtube in HD 1080p?? Overclock or Sonnet dual 1.8 ghz??