link parameters SEO effect

Hi,
on my website i want to know on which of a few links pointing to the same page more people press (for example a picture or the text beneith?),
what is the best way to do this, i myself added a parameter to the end of the link with different values according to where the link is. so i have two links to the same page with the same address, same parameter just different values to the parameter so i know if the picture link was pressed or the text link!
I was told this is damaging as far as seo's are conserned - but this sound strange to me as everybody uses parameters to pass info? is it true or not? please help

thank you
Nat

The only 'damage' it could do is to dilute PR flow, I believe. I'll explain what I mean. If you link to somepage.htm?param1 this link will probably not count as a backlink for the page somepage.htm . But if you don't care about that, and only want to experiment for a couple of weeks, it's a very good method in my opinion.