A single Windows 7 instance for Paralles and Boot Camp?

[stomgb]

I apologize if there is a older thread about this topic. If this is the case, please direct it to it.

I have a MacbookPro Retina 15'' running the latest Mac OS X.
I am trying to find out if it is possible to have a single Windows 7 installation that will serve both Parallels and a Boot Camp boot.
For gaming I need to boot to Windows to enjoy the full capacity of the MBP's hardware. However, for daily use I want to benefit from the seamless integration of Windows in Paralles.
I want to spare the 20GB of disk each Windows installation requires.

What is the preferred setup?
1. Two separate Boot Camp partitions with two separate Windows 7 installations?
2. One Boot Camp partitions with two separate Windows 7 installations?
3. One Boot Camp partitions with one Windows 7 installation?

Thanks in advance,

Tom

 

[NetSlut]

I have used the single instance setup with Windows 7 for years, with no problems.

To install, I created the boot camp partition first and set up W7, then when it had finally updated itself I imported the partition into Parallels. I had to call Microsoft to get the install key authorised for the VM setup since the hardware ID wasn't the same as the Boot Camp version, but as soon as I explained that it was a VM running on the same computer and both versions couldn't run simultaneously, they were more than happy to give me the authorisation code.

Hope that helps, feel free to ask anything more about my setup/configuration/experience with this style of installation.
Ian