Bonsoir Luc,
Many years ago, when Win7 was released I used a bit XP mode... virtualization was something new. I was working for some ok, and was a work around for applications incompatible with Windows 7. But the applications used were mostly home business software. I never dared to try Hauptwerk in such environment.
On the other hand I tried about 8 years ago Vmware Worstation on Win7... and installed Hauptwerk for fun, to see. Forget it... Hauptwerk needs a lot of resources and the timing (midi and audio streaming) is critical, awful latency, audio drivers problems etc. Great to run business applications... not for real-time application like Hauptwerk and audio - https://communities.vmware.com/thread/614502
You may want to consider buying an external audio interface like the Focusrite 2i2 (if you need only 2 channels or 4i4 if you want built-in midi) ... not very expensive and you would at the same time get a much better sound than your built-in audio interface.