This is rather sketchy ground, and no answers here should be accepted as completely correct. However, I will try. I'm going to be looking at Windows 7 Home Basic Retail, OEM will be different. And difficult, since OEM copies are often hardware locked, by license and/or activation method.
The Windows 7 Home Basic EULA has a clause specifically on virtualization (3. d.):
Use with Virtualization Technologies. Instead of using the software directly on the licensed computer, you may install and use the software within only one virtual (or otherwise emulated) hardware system on the licensed computer. When used in a virtualized environment, content protected by digital rights management technology, BitLocker or any full volume disk drive encryption technology may not be as secure as protected content not in a virtualized environment. You should comply with all domestic and international laws that apply to such protected content.
Note it says instead of using the software directly. Though this is rather vague, there are some discussions on such on the VirtualBox forums, one this one in particular explicitly states this is not allowed.
On a more thorough read, I also came across this clause in the same EULA (1. b.):
License Model. The software is licensed on a per copy per computer basis. A computer is a physical hardware system with an internal storage device capable of running the software. A hardware partition or blade is considered to be a separate computer.
Hardware partition could mean physical drive..?
I would say you should not be running (i.e. have installed) more than one copy on the same Key at once. I will also reiterate that I am in no way a legal professional and any advice I may have given could be incorrect.
Are you wanting to run win7 on one partition and then win7 guest in vm on linux host in another partition, with one lic ? This may help you. http://superuser.com/questions/386492/can-i-install-original-copy-of-widows-oem-on-more-than-one-partition-within-th#comment435800_386492
– mic84 – 2012-02-12T14:54:24.730And this
– Raystafarian – 2012-02-12T14:56:33.620@mic84 That's dealing with Windows XP, which has a different EULA. As I understand it, Windows Vista was the first (Standard/home? Not volume-license/server?) to address virtualization directly in the EULA. – Bob – 2012-02-14T01:39:40.607
@Raystafarian That one is talking about reinstalling an OEM copy (again, different EULA), and only one copy installed at a time - the computer was reformatted between installs. With licensing, these distinctions are important. – Bob – 2012-02-14T01:41:33.757