"in answer to your question, mj, wither the P4 or Xeon is capable of addressing up to 64GB of ram(it doesnt have to be a 36 bit processor as 36 x 2 doens not = 64, it is 32 x 2, 36 bit doesnt even make sense as most computer specs are based on the powers of 2 which 36 is not."
Oi? To address 64Gb of RAM you need a 36bit addressing system.
2^32 =~ 4 billion
2^36 =~ 64 billion
Hence the need for a 36bit addressing system to address 64Gb of RAM. As you stated earlier
2^64 =~ 16 x 1000 x 1 billion
So I can't really see how that answers my question.
A 32 bit processor (Pentium class, Xeon class) can only address 4Gb of RAM and that is all. Period.
As for the website, quickly note that there is no such machine as a single 2ghz G5 as the test was done against and you will see that the int test was simply to benchmark fairly with a 3.0ghz processor. As you will note, the P4 was rudely hammered in the floating point arena by ~24%. Add a second processor as the machine has and there is an even slighter difference.
Obviously as the spec benchmarks don't support Altivec (the PPC 970's special instruction set which contains 128bit instructions with 128bit memory pipelines) then we are not seeing the full story for optimized applications. Altivec on the G4 generally gave a 3.2-8x faster performance than standard code. On the G5 we will probably see a 2-3x faster performance (as was seen in the HMMer test on the performance page.