HRoth - 1:15 pm on Dec 5, 2007 (gmt 0)

I wasn't sure where to ask this. I searched but didn't see any definite info one way or the other about whether links from Wikipedia have a good, bad, or indifferent effect on ranking. I ask because four of my top ten links are from Wikipedia pages. These point to pages where I do sell a product but where I have a lot of information about it, and that's why someone put the link. Other than bringing visitors, does this affect ranking for those pages? Does it affect the ranking of the site as a whole?