I can't see how this would work while PCs have socketed components. We have a rating system now, the Windows Experience Index (I hate Microsoft terms!) which attempts to set a standard performance figure for the relevant parts of a system. Unfortunately no vendors of hardware are interested in a standard, honest rating system since profit can be derived from understanding the value of a product more than the consumer.
Do you guys think a non-socketed PC product with integrated CPU/MB/RAM/GPU will ever come about? Generally speaking I buy all those in sync with each other, I don't think I would feel I was giving up anything if I bought a single hardware piece to do all that if the rest of my PC was like it is now. Then you might have a chance of standardising the measurement of PC performance. Maybe after a few years of acquisitions a company will be in a position to give it a crack!