Open Source Content Management

So - I run a couple of online stores.

Recently I've been thinking more and more about navigation.

I like a simple menu in the sidebar linking to all of the categories.

Lately I've been putting my menus on the right hand side of the website.

I feel that previously the left side was the most popular.

What side, left, right or top (as additional link below the main menu) do you prefer an ecommerce website's categories to appear on? and why?

If you mean like a main navigation, then I prefer my menus on the left for an e-commerce site. I enjoy using the right menu as well on a lot of other sites. On an e-commerce site, I'm looking for a specific category, my brain basically goes to the left of the screen for ease and repetition reasons.

Although it depends very highly on the user and their preference.
It all boils down to what the user is familiar with. Taking the transition for the Start Menu from Windows 7 to Windows 8. Majority really hates it, because it changes the way you normally do things. Some users are scared of change..