If your knees are getting in the way, you may try this variation of the DL. I saw it in this month's ed. of Muscular Development. I ignore the pro's training day setups, and most of their recommended exercises (like bicep curls, and other single-joint movements) but Warren Branch was dling with one leg in front of the bar, and the other behind it, it looked weird, but it seems to work. I'll try it out the next time I go lift.