Well, since I now have a 64-bit CPU, it makes perfect sense to install a 64-bit Operating System on it, doesn't it?

After (finally) getting Windows XP 64-bit (beta) version installed, complete with 64-bit driver versions for my graphics card and CPU, I discovered that:
a.) There seemed to be some issues with the OS recognizing my some of the items on my IDE bus
b.) Most existing applications (at least that I use) are still 32-bit.
c.) Microsoft (in their infinite wisdom
) doesn't seem to support 32-bit apps in their 64-bit OS (even though other OS's {i.e. Solaris} do so easily) !
So, in short,
Mozilla Firefox would
not run under the new Windows XP 64-bit OS, which was enough for me to replace it with the 32-bit version.
Here is a
good article that details some performance benchmarks that were run comparing
Windows XP 32-bit vs Windows XP 64-bit.
FYI: The
Arstechnica web site also has a good
article, which serves as a good introduction to 64-bit computing.