How to remap finder folder navigation shortcuts? I don't like  the default finder navigation shortcuts command-up, command-down because you need to press 2 buttons instead of 1. On windows, delete leads to previous folder ("back") and enter enters the folder instead of renaming it like on the mac. 

I have already tried in system preferences but mac os won't let me enter delete or enter as a valid shortcut key. 

Thanks
Check out Keyboard Maestro http://www.keyboardmaestro.com/, it should do what you want. I know it is not exactly cheap for a utility app, but it does a provide a huge amount power beyond simple key remapping, and it has proven to be stable across many Mac OS X versions.