Can Windows 7 upgrade create multiboot?

That will be interesting to see since you can run the installer while booted in Vista for a custom install to a D primary while there. For XP?

That's takes a boot off of the full version disk as a rule to custom install to a second primary if XP is already on the same as with Vista except you can run the installer while booted in Vista but can not when booted in XP! 7 is the upgrade for Vista being the next version inline there.

For setting up a dual boot with XP or Vista installed after 7 once the upgrade takes place where you then add one or the other into the 7 BCD you will need to review the two guides written on dual booting.

For a dual of XP along with 7, Dual Boot Installation with Windows 7 and XP

For a dual boot of Vista with 7, Dual Boot Installation with Windows 7 and Vista

The upgrade kit will simply be the upgrade disk itself along with a paperback boot included in the retail package on 7. That's typically seen with any retail purchase of any version of Windows.

The first to know about upgrading Vista is that the Business edition of Vista would allow the immediate upgrade to 7 Pro. The Home Premium or Ultimate editions will not! The editions have to match for that to work.

The upgrade discs are supposed to have the full OS on them (just a upgrade license attached, to my understanding)> I would also like to know how that turns out myself

Vista Home Premium->7 Home Premium
You can install 7 in a clean partition...its just gets a little odd

Here is some steps...
Install 7 (don't enter your product key!!!)
boot into 7 when its done and run setup.exe off the 7 DVD
Install 7 on 7 (I know...just trust me) and enter your product key now
relax your done

I'll be skipping right over both of those here for the Ultimate once 7 is out. The clean install method for an upgrade disk would also apply to the Pro edition as well as the Home Premium since you already have a genuine disk from a previous version if called for.

A new XP system? I have to build another case to upgrade a family out of XP Pro into 7 Pro since that will support virtualization and of course seeing XP Pro in the XP mode there to begin with.

For a basic machine without all that then you would see the Home Premium edition go there. You kind of have to weigh the differences between the editions. The one way to decide is to look over the comparisons based on your own user preferences as well as simply grabbing the promotional discounts. Compare Windows 7 Editions