tedster - 2:49 am on Sep 14, 2009 (gmt 0)

Your current set-up is actually a good practice. Simply Disallow the /visit/ directory in your robots.txt and you are good. The nofollow attribute is also a good practice but there's no need for you to make all those changes because you are already in good shape.

I would not suggest going to javascript because Google is already spidering and indexing some javascript links.

I heard Google lowers a page's score in the presence of affiliate links

I think that's just a bit off the mark. Google may lower an affiliate page's ranking when the content on the pages is not unique or if the site does not offer visitors some extra value, over and above showing the same products and information that other affiliates of the same business offer. There's no automatic lowering of a page just because it serves an affiliate link.

The simplest way I've heard this said is "create a valuable site first, then it can have affiliate links". Going the other direction is what makes trouble.