It's getting hot out here!
Guess I should pour some water...
To the end user, what matters is the real world performance tests, such as actual encoding tests, actual gaming tests, actual rendering tests, actual database tests and actual math/scientific tests. Why I emphasize on actual is because there are synthetic tests for all those categories.
Synthetic tests do have their purpose. For an overclocker, synthetic tests help determine QUICKLY if his overclock really worked. Also, to compare two products of the same family, say for example E8400 vs E8600, it helps determine what sort of real world result one can get. E8400 vs. Q6600 isn't a fair comparison in these synthetic tests, because synthetic tests usually do not give a generalized view of the CPU's performance as the real world tests do.
------
Why you don't see a performance difference with your PC and another with a C2D in
GAMING is because your PC maybe is a balanced PC for gaming. I maen, your VGA might not be bottle-necked by the CPU. To get the best performance of a C2D, you need a highend VGA because otherwise the CPU will be waiting there for the VGA to do its thing. Then again, if you go for a good VGA, you need a bigger monitor to support the VGA's capabilities. Basically, you need to plan everything.
But this is not to say that everything also needs to be balanced. For someone who doesn't play games, there is no point wasting money on a VGA. But I see people buying Quad Core CPU's and just 1GB RAM and a 160GB HDD. That is utter stupidity. You get the quad core to do more work at the same time, but without RAM, how can it run more tasks at the same time? Always page in and page out! Then, you buy Quads to do video encoding and rendering, which need a vast amount of disk space!!! WTF are those apps gonna do with 160GB space??
Like wise, having the fastest *single* component doesn't mean anything. It's the setup for the requirement that matters.
Note: There are, however, synthetic benchmarks that give an overall idea about a PC. Eg. PCMark Vantage. It's actually not synthetic, because inside it, it runs many "real world" applications (not programs; APPLICATIONS)
Note2: Did I pour water or more fuel?