Great, thanks for the input.
It made me analyse several options.
Not as straight forward as i had expected.
(And more so primarily expected from Opera's ease of config)
In short i chose to junction the Opera dir in Program files(x86) to a portable (usb) install on the secondary partition.
Cleaned up the now obsolete conventional install Opera residu, but leaving the Windows (7x64) assets beeing the default browser setting and more.
There are several reasons for this approach. If one's interested we could eleborate on this, but for now im setting my issue as solved, and testing daily functionality.
Sofar the results are oke.
Thanks for the fast reply's!