I just read the January 2004 Cadalyst magazine and spotted an article error or confusion point. The error or confusion is an easy one to fall into in fact I too was thinking the same misconception awhile back until I researched the 64-bit processors from AMD and Intel in greater depth for my floating point (accuracy/prescision) posts in this blog titled 64 bit Computers & AutoCAD, More on 64-bit Processors and AutoCAD and also, More from the AutoCAD Accuracy Universe and the Floating Point.
You cannot connect the 64-bit processor to greater CAD accuracy or precision, but that is just what the article "HP Pioneers 64-bit Computing" did in it's table "How Does 64-bit Computing Compare to 32-bit."
The article is correct in the accuracy of 64-bit floating-point precision, but did not mention that AutoCAD has had 64-bit floating-point precision since the early 1980s. You do not need a 64-bit chip to get 64-bit accuracy, as it is already on their 32-bit processor. In fact you can get a maximum of 80-bit on the 32-bit processor. The 64-bit processors do not provide any benefit to precision. The main benefit of 64-bit is the addressable memory, which does not equate to precision. You do not really gain any speed at this point either.
I do not think a true 64-bit native application for CAD is any benefit to the majority of CAD users unless they are dealing with models that require more addressable memory space and have extra cash burning a hole in your pocket. Currently with the AMD 64-bit chips, you can install your current 32-bit applications and in the case of AutoCAD 2004 it runs up to 40% faster with no porting. The AMD 64-bit runs 32-bit applications in a native mode and with the benefit of a faster bus speed of almost double the Intel and faster floating-point calculations, which CAD requires for accuracy. Intel’s Itanium cannot run the 32-bit applications natively, and emulates the 32-bit environment, and makes them actually slower currently. There are also no real 64-bit tools or operating systems except a Microsoft Windows XP 64-bit for the Intel only platform but the AMD version of Windows 64-bit is coming later this year.
My personal suggestion if you want a 64-bit machine is to get the AMD so you can run your current 32-bit applications and gain performance in many cases at a low price of about the same as a 32-bit machine. Alternatively, you can wait and see how the industry solves the current two separate 64-bit platforms and hopefully one emerges so there are not multiple versions of the operating systems and applications. The future may be 64-bit, but it will take some time to see a clear safe path to it.
Remember 64-bit does not mean greater accuracy in most cases as AutoCAD has had 64-bit accuracy in the 32-bit platform for many years although some CAD systems such as Bentley just recently got the 64-bit floating-point accuracy, the 64-bit processors are really not needed for this ability.