For those concerned with making OB2 fly on Win7 (64bit), I am pleased to report that it does infact work.
Stability may be another question (I only just got it working, will need some time to try it out.)
What made the difference for me (aside from the driver signing matter), was this post.
It strikes me as counter-intuitive to have the device (Digitakt in my case) on & attached ahead of installing the software.
In my experience this is directly counter to what generally works for installing new USB hardware.
Good luck and happy beats / samples / blorps! 