Remember that google is the best because they are more advanced. I'm willing to bet that the PR for things like links would be helped by alt tags a lot, but also your descriptions. They don't necessarily have to be inside the link, but google like content.
Have the links in a paragraph of text full of keywords, I bet you'll get higher click thru's for one, but more chance of google finding the link more relevant.
Have the links in a paragraph of text full of keywords, I bet you'll get higher click thru's for one, but more chance of google finding the link more relevant.