My ZDNet colleague George Ou has a very nice introduction to the differences between 32-bit and 64 bit Windows. If you’re planning a new PC purchase and weighing the pros and cons of the x86 and x64 architectures, it’s worth reading.
A primer on 64-bit Windows
Published
Ed Bott (@ wordpress.com) 
The drivers are pretty bad, and I have yet to see any conclusive benchmarks that show a significant gain in performance in a 64-bit env. The only gain i see is the larger addressable memory space…but for me that’s pretty useless because the only apps I have that could possibly use the memory are games…and games without good sound-drivers or graphics drivers that work in x64 are unplayable anyway. Add to the fact that EAX won’t work without an OpenAL hack (and i do mean hack…the hack itself is still in beta!) in Vista, the future of x64 in vista begins to look still further off…
The driver issue forced me to stay with 32-bit for the time being. I have a printer and a scanner, neither of which I can really afford to replace, which are 32-bit only.
Thanks for the tip to Ou’s article. I build a new machine every four years, and my old one was fine, I chose the 64-bit OEM version of Vista, along with a 64-bit chipset. I understand that it will take the rest of the year, maybe more, for the machine to see its potential, and I can suffer that. For now, I got great prices on everything, essentially building a $6000 machine (from Dell, Alienware, HP) for less than half that price. Heck even the best 22-inch flatscreen monitors can be had for $300 right now. Depending on next year’s chip scene, this may become the wife’s machine in 15 months.