The benefits are mostly high-end as you'll see from this link...
<a href="
http://www.microsoft.com/windowsxp/64bi ... top10.mspx" target="_blank">Top 10 benefits of Windows XP Professional x64 Edition</a>
You'll also find that there are free 32bit apps out there that have been disabled for 64bit requiring you to buy them. For example AVG Free Edition and other Grisoft products. In addition to this there are 32bit apps that are just plain incompatible.
I've got XP 64bit on my wife's machine, the incompatibilites were more of a nuisance than a problem as I then just had to look for alternatives.
If you wanted to experiment with XP 64bit now would be the time to do it in your case because if you're not happy with it not liking the kind of software you intend on reinstalling then you haven't done too much to then revert back to XP 32bit.
More MS stuff:
<!--quoteo--><div class='quotetop'>QUOTE</div><div class='quotemain'><!--quotec-->Comparing 32-bit and 64-bit editions of Windows
The major difference between 32-bit and 64-bit editions of Windows is memory support. With more memory, you can run more programs at the same time, and run more memory-intensive programs like multimedia, gaming, and database programs. And your computer's performance will be faster overall.
Currently, 32-bit editions of Windows are capable of supporting up to 4 gigabytes (GB) of system memory, with up to 2 GB of dedicated memory per process. Windows Professional XP Edition x64 currently supports up to 128 GB of RAM, with the potential to support up to 16 terabytes of virtual memory as hardware capabilities and memory sizes improve.
Another difference between 32-bit and 64-bit editions of Windows is the increased number of registers available on 64-bit processors. This enables faster performance for applications that perform intensive floating-point calculations.
Windows XP Professional x64 Edition provides faster performance, increased reliability, and greater flexibility to today's most demanding users. With Windows XP Professional x64 Edition, you can take advantage of the new 64-bit technology to improve your PC or workstation performance.<!--QuoteEnd--></div><!--QuoteEEnd-->
<a href="
http://www.microsoft.com/windowsxp/64bi ... nefit.mspx" target="_blank">More MS info...</a>
Just be a nutter... life becomes much more exciting, and people won't expect anything more of you...