Explorer Backgrounds do work in XP
Importing & Applying a Skin with Skinstudio may do the trick
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I have been evaluating Windowblinds 6.1 on my XP Partition. After installing it, It said that the this feature can't be enabled in XP.
But here's what I found out. I opened up Skinstudio and opened my custom made skin that I made with Vista. After applying the skin in XP, the explorer background changed to the same background as in Vista. However, the transparency feature doesn't work.
This only applies to Windowblinds 6.1. Earlier versions won't work. I will upload a snapshot of my new XP configuration sometime to show people that this does work.