AMD Athlon64 - 64-bit vs. 32-bit, A Head On Comparison
 

A new era of 64-bit computing is coming though, and it got us to thinking... what does 64-bit, specifically the 64-bit support built into AMD's Athlon 64 and AthlonFX processors, have to offer the gamer and enthusiast markets? In this article PCstats will examine the performance of the AMD Athlon 64 processor using conventional Windows XP and 32-bit benchmarking software, and compare those results to the same tests using the 64-bit 'x64 edition' beta version of Windows XP.

http://www.pcstats.com/articleview.cfm?articleID=1665