Hello,
If you create a 150 GB Windows partition for Boot Camp (it will be constantly formatted as NTFS so you left 256-150 = 106 GB for Mac side, just to note) and then you create a virtual machine _BASED_ on the Boot Camp partition -> The virtual machine on the Mac side will be just a "shell" for the Boot Camp partition mostly to forward system calls to Mac OS. So the virtual machines size will be less than 100 MB or so. In this scenario you should have enough space along with ability to boot directly to the Boot Camp or running Windows from the Mac side.
Couple of words regarding "I'm scared that using the VM on its own, I won't be able to run my hardware/software"
The virtual machine states for the real computer and the software should work on it just as it was a real physical PC. The same with the external devices e.t.c. With comparison to Boot Camp, the virtual machine has an ability to create a Snapshots (you may save the state of the VM anytime and revert to it back if needed). It is a strong tool in terms of security and safety. Boot Camp does not have such, so you can't back up the VM like that. Please also consider that the Boot Camp based VM also does not have Snapshot feature.
In sum - both scenarios are acceptable, but assuming 256 GB SSD drive, you may experience space issues on the Mac side if you install Boot Camp first.
Last edited: Aug 14, 2014