What You Don't Know Can't Hurt You

If you own a AMD Dual Core or 64bit processor you might not be getting the most out of it.

Main Update Link

http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_9706,00.html

XP

AMD Athlon™ 64 X2 Dual Core Processor Driver Version 1.3.2.0053 for Windows XP and Windows Server 2003 (x86 and x64) - Allows the system to automatically adjust the CPU speed, voltage and power combination to match the instantaneous user performance need. This package is a user friendly localized software installation of the driver designed for end-users. This driver supports AMD Athlon™ 64 X2 Dual Core processors and supports future quad-core upgrades on Windows XP SP2 and Windows Server 2003 SP2 x86 and x64 Editions

AMD Dual-Core Optimizer for timing by directly using the - The AMD Dual-Core Optimizer can help improve some PC gaming video performance by compensating for those applications that bypass the Windows APIRDTSC (Read Time Stamp Counter) instruction. Applications that rely on RDTSC do not benefit from the logic in the operating system to properly account for the affect of power management mechanisms on the rate at which a processor core's Time Stamp Counter (TSC) is incremented. The AMD Dual-Core Optimizer helps to correct the resulting video performance effects or other incorrect timing effects that these applications may experience on dual-core processor systems, by periodically adjusting the core time-stamp-counters, so that they are synchronized.

Linux

AMD Athlon™ 64/FX Cpufreq Driver for Linux 2.10.00 - Allows the system to automatically adjust the CPU frequency, voltage and power combination that match the instantaneous user performance need. Supports all AMD Turion™ 64 Mobile Technology, AMDOpteron™ Processors, and Athlon™ 64 Processors released through 2007. Provides support for AMD PowerNow!™ technology and, where appropriate, AMD’s Cool-n-Quiet™ technology for Linux systems. Works with all kernels, version 2.6.10 or later. Requires the ondemand kernel module or the cpufreq-1.20, cpuspeed-1.20.1, or powersaved-0.8.19 or later user programs to support SMP and multi-core systems. This driver is already included in the 2.6.18 or later kernels and does not need to be downloaded again.

Its best to visit the main update link to find the latest download for your CPU