Captain Bob is correct. It's a simple chip swap, but you'll have to attend to a few minor software details afterword. It's been a few months since I've done this. Befroe you proceed, there may be a new point-n-click-shortcut for the alphabet soup below, so check out the following link to our friends over at XtremeSystems:
http://www.xtremesystems.org/forums/showthread.php?t=81429
(1) Download and install amdcpusetup.exe
(2) Download and install WinXPdualcorehotfix.exe
(3) Edit your Bootini file as follows:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOW S
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /usepmtimer
(4) Edit your Registry as follows:
1. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager, New, then click Key.
2. Type Throttle for the new key name.
3. Right-click Throttle, point to New, and then click DWORD Value.
4. Type PerfEnablePackageIdle for the value name.
5. Right-click PerfEnablePackageIdle, and then click Modify.
6. In the Value data box, type 1. Make sure that Hexadecimal is selected in the Edit DWORD Value dialog box, and then click OK.
Hope this helps. Good luck and enjoy your new CPU!