Sure. I'm not so dumb.
Dell and all the other branded names CDs - are known as OEM SLP CDs.
OEM - Original Equipment Manufacturer
SLP - System Locked Preinstallation
Together, it's just one license which has been pre-activated and locked down to just a particular set of hardware.
That's a reason why such CDs will never install on another one, unless the specs are the same. But even that offers no guarantee, because once activated, the license is deemed as used and WGA will treat the machine as a pirated one.
As for the Vista to XP issue, read here:
http://www.news.com/The-XP-alternative-for-Vista-PCs/2100-1016_3-6209481.htmlThere's also another upgrade issue:
http://www.whatthetech.com/2007/01/29/vista-upgrade-invalidates-your-xp-key/Upgraded PC = cannot downgrade. Effectively, you have to do this:
1. Wipe the data off the hard disk (either using softwares or wipe out the current one using another OS other than Windows)
2. Buy a new Vista INSTALLATION disc
3. Buy a new XP INSTALLATION disc
For anybody who has upgraded to Vista not using the installation CD but UPGRADE CD, you have no other choices. You can't downgrade without buying a new Vista and XP CD. Of course, you could save money buy just wiping it out and not installing Vista again.
For those who got a brand new machine, you can only perform a downgrade if your OS meets CNET's article requirements. Those who bought from some branded names companies, your bet is don't try. They might have upgraded the XP to Vista rather than a fresh install, so as to save costs.
The best answer is to call up your manufacturer and ask them to perform a downgrade for you.