Originally Posted by Martin Cracauer
If you are rubbish busting, you may want to be more accurate. There is almost no chance of 64bit code running slower than 32bit code. And while the 64bit chips will run most software at equivelent speeds in 32bit mode, some applications, like MySQL, will see a marked improvement in speed. Running 64 bit will also allow the computer to take advantage of many of the new processor commands that are not present in the 32bit spec.