My head can't keep up with all of the posts, but I did want to point out something from Dr. Hofve's site:
NOTE: Consumer Lab® released a report in December 2009 regarding test results from 10 commercial milk thistle preparations. Only Jarrow Formulas® Milk Thistle contained the industry standard 70% silymarin; all the rest fell short. They suggest using a product containing milk thistle “seed extract” as opposed to “seed powder” or “whole herb” to get the most silymarin.
If you're not worried about potency as much, then don't worry about the above, but just be aware that other brands may say they have x% milk thistle extract but may actually have even less.