I use VimNotes to take notes, but the capital N in Note command is really annoying me. Yes, I always have to use Shift to type : but still dont want to type capital N.

The :command seems like a viable option at first:

                                                  *E174* *E182*
:com[mand][!] [{attr}...] {cmd} {rep}

        Define a user command.  The name of the command is
        {cmd} and its replacement text is {rep}.  The command's
        attributes (see below) are {attr}.  If the command
        already exists, an error is reported, unless a ! is
        specified, in which case the command is redefined.

However, there is a restriction on user-defined function naming:

:command Note note
E183: User defined commands must start with an uppercase letter

But there is another way, abbreviation:

                                               *:ca* *:cabbrev*
:ca[bbrev] [<expr>] [<buffer>] [lhs] [rhs]

        same as ":ab", but for Command-line mode only.  {not
        in Vi}

When you type in like (underscore indicates the cursor):

:note<space>_

It will then be replaced with, as soon as the Space hit:

:Note _

Note that tab-completion with commands will not work, :note<tab> does nothing. You will need to press space for the real command replacing, then Backspace and Tab in order to get the completion working.

This is the only way that I know how to have close to command aliasing, if you know a better way, please do share.