ssh in from macbook pro to saiwaves and others

First I tried the default method given in my earlier post. The thing to remember is, how to navigate to hidden folders in Finder - use the Go Menu -> Go to Folder (Command+Shift+G)

Tried by copying the contents of the id_rsa.pub from a Windows machine into the ssh terminal there, to the authorized_keys file. Did not succeed. Permission denied (publickey)

Thought it might be some permissions problem, tried changing

chmod 755 .ssh - still no go. So changed it back to 700.

Some posts suggest using DSA instead of RSA on OS X. "Don't use RSA"! So, tried with DSA as given here, using ssh-keygen -d instead of ssh-keygen -t rsa and also not copy-pasting the key from Windows or Mac but instead doing a cat id_dsa.pub >> .ssh/authorized_keys2 - this time it worked immediately.