Think again...
http://www.infoworld.com/articles/tc/xml/01/10/29/011029tcwinxp.xml
In fact, until 2GHz desktop PCs become commonplace, we have a hard time recommending widespread adoption of Windows XP at all. Granted, it appears that for light-duty service on the newest hardware, Windows XP with Office XP is an acceptable choice -- if an 11 percent performance hit, or 53 minutes added to an 8-hour day, is acceptable.
http://www.infoworld.com/articles/tc/xml/01/10/29/011029tcwinxp.xml