Conditionally make thick border

I am trying to make a conditon where the left border becomes a thick line if certain criteria are met. I am using Excel 2007 and I do not see the option in the formatting section. There are several styles of broken lines but no thick border. Is this an option?

It's not, but there are options. Can you further describe what you're trying to accomplish with the thick border, and why it needs to be this way? If worse comes to worse, a macro can be developed and tied to worksheet calculation to give you the border you're looking for, but it's not an optimal solution.