dark_lord69 :
I believe that the features offered in the Professional and Ultimate versions are not worth the extra money. As they are features aimed at businesses.
You likely: Don't need to add your computer do a domain. Don't need to Run XP Mode (it can't play 3D games anyways). And I doubt you need the ability to boot from a virtual drive. These are features that the average Joe OR the average computer tech (such as myself) don't need....
A corporation on the other hand would definitely want these features. Most company's run a domain which would require thier PC's to be at least Windows 7 Professional. If they wanted that computer to be able to boot from a virtual drive or allow that person to have a more media rich experience then they would go with Windows 7 Ultimate.
I would say for ALL home users (Gamers, Computer Techs, it doesn't matter) you should just buy Windows 7 Home Premium.
Not all of the Professional and Ultimate features are strictly aimed at businesses. Average Joe might have some app that simply refuses to run in 7, therefore making XP Mode useful which of course Home Premium users are not licensed for.
With computer thefts (especially laptops) being more widely advertised by the media, EFS and BitLocker become more attractive (yes I know there are other options out there like Truecrypt, but hopefully, you see my point).
This one is rare compared to the other points above, but there are people out there running domains on their home networks. I personally am not one of them, but I know a number of people doing this. Granted, they work in the IT industry like myself, but they are home networks all the same.
So no... not ALL home users should blindly buy Home Premium. They should first determine what their specific needs are, and make a choice based on that.