So my 4 year old Sony Computer is starting to act up. The video card died a couple of weeks ago and now the power supply seems to be going. I have not kept up with computers over the last couple of years and am completely clueless on this dual core/quad core thing. I see that there are quad core compters with 2.4 ghz processors available for a good price. The current computer is a 3 ghz,, so whats the deal??