aristotle - 5:10 pm on May 18, 2010 (gmt 0)
Some SEO experts say that you shouldn't use the exact same anchor text on all backlinks that you create, because it wouldn't look natural to the Google algo. Instead, they recommend that you vary the anchor text.
Of course you should use at least one of your main keywords on most of the links. One idea is to make a list of different combinations of keywords plus other words that appear on the page.