TheEnd, as to your question on 360 memory speed, the bandwidth on the 360 between memory and processor (both GPU and CPU) is VERY wide, actually wider than the PS3. The 360 does not have problems with bottle necking. There was fear that the PS3 would have this problem, because the bandwidth was so narrow in comparison with what the the cell could do, but some ingenuity on the part of Sony allowed the cell processor to do many of the FP calcs and on the fly calcs in the cell processor itself without a memory dump. This info was also able to be verticed without sending to the GPU for display. The 360 also does this, to a point. However, as in what I've listed above, these similarities stop right there and that is where the GPU on the 360 cuts above the Cell, because the architecture is better thought out and more powerful. Now, Sony has something up there sleeves for this, though. The original idea was for the Cell to be both the CPU and GPU, ****... it's powerful enough to do just that. Problem with this is that development is hard enough without now using all those SPE's and single genearl purpose core to now do graphics, and was just not realistic so they got NVidia to make the PS3 card later in the creation of the PS3. This is a good thing, and a bad thing. A good thing in that programmers will have an easier time now, but a bad thing in that the card would not prove near as powerful as their rival and so to match this they would have to fall back somewhat on using both the cell AND the GPU in tandem to make up the power difference. This is bad news, because it is VERY hard to do this. That is why I say the PS3 has SO MUCH POSSIBILITY!!! However, the software development industry has to catch up and think new rules in the game of programming, and by the time this happens I have the feeling it will be around the time of new console arrivals, and possibly a new king on the block.
To sum it up, great system, true. Not practical in important ways, and much of what they are doing is to little to late.
Now, onto memory specs. Here is some info on how the core and other parts work... part II
Inside the Xbox 360, Part II: the Xenon CPU: Page 1
Like I said before, I'm not anti Sony, I just think they tried to much at once, and it will turn and bite them on the ***. The cell is very powerful, but to match the GPU capabillites of the 360 the cell needs to be used in combination with the PS3's GPU, which was added to remove the need of using the cell for graphics use in the first place due to difficulties. This makes the Cell not really built for gaming, but scientific use. Now, if Sony had waited for a more robust and powerful GPU, God this thing would of been unstoppable but with MS 1 year ahead already and Nintendo releasing soon they didn't have time to spare.