Its rock solid for me on win7 x64. one suggestion though: you might want to do a custom install and untick the behavior shield, as it doesnt do anything yet
on 64 bit.
I disagree to that. Behaviour Shield does work on x64 system - it just happens that there are no rules defined for x64 systems atm. (BS is rule based). As soon as the need arises, rules may be implemented by virus def update. So it's a better choice to install the BS, even though it does not scan anything right now - but it does not have any negative effect on performance. At least on my system.
So I'd recommend installing it and have it ready to work.