If you have a normal native install and you use parallels you can have it use the native windows installation as a boot camp vm.
That is exactly what I do. I partitioned my System drive in two partitions, with a native Windows 7 and native OS X install. And this Windows 7 partition also doubles as a parallels installation. So it would be important for this to work exactly this way also on a hackintosh. But I am not sure if it will be more hassle with the partitioning, since I also want a recovery partition. So an option would be to use just a separate drive for windows. That's one of the open questions I cannot answer right now.
I rarely if ever boot windows natively anymore.
In many cases I do that as well. As I mainly use VMs for software testing, it is quite common that I have 4-5 VMs open at the same time. I would also like to open more, but this is the point where my Mac Pro begins to bog down with only 16 Gigs of RAM (also CPU load is quite noticeable, with a total load - ie all 8 cores - of up to 50% even when the VMs are more or less idling).
But: as I wrote before, there are cases where I just need or want a native install:
- I need native booting for some software I use that demands a more direct access to hardware. In my case, drivers for an USB microscope as well as the windows phone emulator.
- I want native booting for gaming. Tried some games (and I don't play _that_ demanding games, no FPS for example) in paralells, and at least with my setup there's a noticeable difference, esp in Graphics