I'm not a fan of security by obscurity.
There's one thing I know: if I were to be malicious and have system rights on your PC, there is no way you can execute a Bitcoin trade without me taking everything from every wallet privkey involved.
Of course, you can try to make it look & feel different by using VMs, weird encryption, blah etc. But in the end, the hacker has your RAM, your keyboard input, your UIs, your network interfaces... no matter how you open and/or decrypt, he can do the same.
Unless, of course, all your software except Bitcoin runs in your sandbox from the moment you installed the system. That works.
i've been looking into qubes. have you taken a look at it?http://qubes-os.org/Home.html