Ok, so you changed the permissions on the directory, but did you change the group?
Originally you had the following for ls -ls /opt:
drwxr-xr-x 2 root root 4096 2010-04-05 23:16 .
And with the above chmod you should now have (I would advise to check this is so):
drwxrwxr-x 2 root root 4096 2010-04-05 23:16 .
But all this has done is allow the group 'root' to now also have write access to this directory.
As you are not in this group then you do not have access unless again using the sudo command.
However, if you were to issue:
This will then allow all users in the admin group to write to this directory.
(Chose admin as you previously indicated you are in this group)