[H] windows 7 upgrade confussion

[Winterlight]

I purchased two Windows 7 Pro upgrades back when they were offering 
them. I have a desktop running Vista 64 Home Premium OEM and a laptop 
I got last year that came with Vista 64 Home premium.  When MS 
offered the Advance copy of Windows 7 upgrades I grabbed two of the 
100 dollar PRO versions, having had my fill of the Home Premium limitations.

In the last month I have been reading confusing stories about Windows 
7 upgrade DVDs which seem to imply that if you are running Vista Home 
Premium, you can only upgrade to Windows 7 Home Premium using a 
upgrade DVD....or if you have Vista Business you can upgrade to 
Windows 7 PRO. Is this apply to everybody or is this just for  those 
who bought a computer and are getting a free Windows 7 upgrade.

Also, if I install my Windows 7 PRO to a separate partition of my 
current Vista 64 OEM desktop, so I can dual boot them. Will Windows 7 
deactivate my Vista 64 after authenticating it for upgrade purposes. 
Or will it allow me to keep running Vista 64 OEM on it's original 
computer. In other words, can I keep and dual boot the Vista 64 OEM 
after installing the Windows 7 Pro upgrade DVD.

Anybody know?

thanks