Look folks, the reason for the extra $50 is simple. You get both Vista AND XP.
I think you're wrong.
I'm trying to buy a Dell laptop today. Here are my operating system options:
Genuine WindowsÂ® XP Professional, SP2 with Media add $0
Genuine Windows VistaÂ® Business Bonus-WindowsÂ® XP Professional loaded [Included in Price]
Genuine Windows VistaÂ® Ultimate Bonus-WindowsÂ® XP Professional loaded [add $50]
Genuine Windows VistaÂ® Business Service Pack 1, With media add $0 (Dell Recommended)
Genuine Windows VistaÂ® Ultimate Service Pack 1, With media [add $50]
You'll notice that (1) XP loaded, (2) Vista Business loaded, and (3) XP loaded plus Vista Business on media are all the same price. It sounds like beginning tomorrow either of the XP options will carry an additional charge.