I have heard that its best to not have a too many collum on your blog especially the left collum hense why you see most site using right collum. I read somewhere that the Google spider goes down your page starting from the header then to your left collum then to your content. Is this true?
This does play a tiny role. But you should not be concerned too much about this. + In general, the link juice towards the higher position on page is little higher than at the bottom, not much different but a little bit.
I could be wrong, but I believe it works like this: In a table-based layout, things are basically read with the left column first, then middle, then right, from top to bottom, b/c that's how the code for the table appears in the html. With a CSS design, like wordpress themes, you're able to position things differently in the code, to have the most important areas for SEO showing first when SEs are reading it, by using the CSS file for positioning. I believe the other benefit in that sense is that, by having the CSS in an external file, it's taking away more garbage from the html that the SEs have to read.