>I am running XP Pro with all of the latest service packs and patches installed. How can I tell what version of installer I am running?

I'm using XP Pro too (Spanish).

msi.dll show version 2.0.2600.0

But I think this aren't the problem if you have XP Pro.

You can try:

http://www.microsoft.com/downloads/details.aspx?FamilyID=4b6140f9-2d36-4977-8fa1-6f8a0f5dca8f&DisplayLang=en

Regards,
José Luis.