Pierre ...
The Windows Setup and Device Installer Services, also known as SetupAPI,
include the Windows functions that control Setup and device installation.
You didn't indicate where, in the course of your installation, you received
this error but have you been able to get to the point where you can read the
setupapi.log?
"Interpreting a Sample SetupAPI Log File"
http://tinyurl.com/hhla
It's possible that your computer might just have upgrade device
compatibility problems ... try running the Upgrade Advisor Tool. You can
run the Upgrade Advisor tool manually by clicking Check System Compatibility
on the Welcome to Microsoft Windows XP page that appears after you insert
your Windows XP CD-ROM into your CD-ROM or DVD-ROM drive. You can also
download the Upgrade Advisor tool from the following sites:
http://www.microsoft.com//windowsxp/home/howtobuy/upgrading/advisor.asp
http://www.microsoft.com//windowsxp/pro/howtobuy/upgrading/advisor.asp
"Description of the Windows XP Upgrade Advisor"
http://support.microsoft.com/default.aspx?scid=kb;en-us;307726
You might also try Start, Run "SFC /scannow" (without the quotes) ...
assuming you've gotten that far.