Spreadsheet:
http://www.megaupload.com/?d=TZ59Y6QL
@Manhattan, your error is that you don't draw cards in a vacuum, you draw hands of 7 cards, as such, you need to calculate the probability of drawing a certain hand. This is called the hypergeometric distribution, it's actually not that difficult, you first look at the chance to draw the card once, this can be the first draw 2nd, 3rd, 4th, 5th, 6th or 7th draw. Then you multiply that by the chance of not drawing the second copy and then add all the probabilities together.