Showing merchant logo rather than text

Morning all,
Well my site is hopefully being crawlled by google and the other search engines now according to my log file - fingers crossed it might be done for this time next year! ;)

I'm trying to change the merchant text to the merchant logo - so when you click product X and you see the merchants names it shows their logo instead. Any ideas on how to do this? I've had a look into the products.php but still not comfortable changing it at the moment!!

Any ideas would be appreciated.

Regards,

Michael