The primary variable of importance for memory is the speed, DDR3 1600 MHz will generally be faster than DDR3 1333 MHz regardless of timings (but not always as we will see later). Of secondary importance is the timings -- CAS 7 is faster than CAS9. Take a look at this chart for DDR3 memory showing the relative performance of DDR3 RAM with different speeds and timings:http://www.tomshardware.com/reviews/core-i7-870-1156,2482-9.html
The key to remember is that memory is seldom the bottleneck in any system. The only reason to get memory with higher speeds is so that you can overclock your processor, and get a little performance boost from your memory.
So, to answer your original question, DDR3 running at 1600 MHz with CAS8 will be faster than DDR2 running at 800 MHz with CAS4. But you really are comparing apples and oranges, and you cannot make any general statements that will be true in all situations.