One limitation with running IIS on Windows XP Pro is that you are limited to running only one virtual server. Steve Cohn has figured out a way to have Multiple IIS Virtual Servers on XP Pro, and shares how to accomplish this in this rather brief, well-written article.
Essentially, while it might appear that Microsoft eliminated the creation of multiple virtual servers, in reality they only hid this feature. Cohn explains how to  make use of administrative scripts IIS  comes with, particularly the adsutil.vbs script. He also covers how to delete a virtual server that you have already created by making use of this technique.