Menus on left or on right

There is a strong SEO reason for placing your main content
in the left column and everything else in the right column.

If you want your pages to rank higher in google you need
to place your keywords as early as possible in the source
code of your pages. That is called 'keyword prominency'.

The ideal source code order is following:

header code
main content code
columns with menus etc
footer code

Search engine spiders read the code from the top of the page
downwards and from left to right.

Your goal is to have as little code as possible above your main
textual content.

That's why you want your text containing keywords to be read
by spiders right after the header code.
If the sidebar is placed before the main text, the spider needs to
read all the way down the sidebar before it comes to your
keywords.

There are some special table layouts that allow you to have both
left and right sidebar while still forcing the spider to read the main
text content first.

You can understand this special layout if you study the source code
of sites generated by XSitePro for example.

Anyway, from SEO point of view it's much better to have your
sidebar on the right side.

It really depends on what you want your visitors to be doing. Upper left corner is prime real estate as shown in virtually all hot-spot research.

If you want them to go deeper into your website, then yes your navigation should be there.

If you want them to sign up to aweber, then your sign up form should be right in that position.

Check out my signature link and you will see that I want my visitors to sign up, without too much concern about where they go within the site.