Here’s the deal. Dell agreed to Microsoft’s plan of allowing Windows XP sales after June 30, but at a surcharge over installing Vista. How much of one? $20 to $50. ComputerWorld says that customers who buy the Vostro (low-end) desktops and notebooks will pay this fee in order to downgrade from Vista, which Dell is still bundling in order to comply with Microsoft’s rule.
https://gizmodo.com/dell-to-sell-xp-after-june-30-microsoft-to-pretend-the-384368
Vista Business and Vista Ultimate—the two more expensive versions of Vista—are the only two available for downgrade, and only to XP Pro. So in order to get XP on a Vostro 1000, you’d have to install Vista Business first, which costs $99 over the default. Then, you’re down another $50 for the downgrade for a total of $149. That’s quite a kick in the nards, Microsoft. Then again, Vista is fine and should work fairly OK on pre-built machines if you want to save $149. [Computerworld]