I've downloaded muCommander and find it better than Finder. When I open folders with QuickSilver it still uses Finder, though. How do I change this behavior?
According to Apple Tech Note TN2062, you can replace the Finder by telling
Be sure to read the entire thing for warnings. It sounds like a risky idea.
If that doesn't work, QuickSilver might be hard-wired to launch Finder. In that case, you will have to contact its developers and ask them for a new setting.
(Note that things like the File > Open dialog will still use Finder, since that is part of the operating system.)