Im only going by my own experience here, but Cache after a certain point, doesnt mean all that much.
I mean, ok, I have had 2 Semprons... A 3100 ( That I still have ) and thats got a 256K Cache, and a 3300 and thats only got a 128K one... The 3300 is a severe pile of junk, while the 3100 is useable, even though the 3300 is 2Ghz and the 3100 is 1.8.
I also got a Newcastle thats got 512K and thats very useable.
The difference from 128k to 256k is big.
The difference from 256K to 512k is still noticable, but not as much as 128 to 256
Now, going over a little here, but I also have a 3800 ( 2x512K ) and a 4400 ( 2 x 1MB ). They both clock fairly well, and, at the same clock speed, there is absolutely no difference that I have found what-so-ever.
There may be with certain things like Video Editing etc, I have not really given them THAT much of a head to head, but I am only going on that idea again, where the cache as it gets bigger and bigger, makes less and less difference.
If there is no real difference between 512K and 1MB, then there is going to be even less difference between the 2MB and 4MB of the C2D CPUs isnt there?
The only real way that we will be able to test this out, is to clock both CPUs to the very same Multi/FSB and hit them with "all you got", but to be honest, I dont think there will be any difference at all.
So, there will be no bloody difference between the C2D CPUs there will there?
There are also many instances where the humble 6300 has proven to be the better CPU £ for £ than its bigger brothers