Benefits of going through Disney are quicker turn-around (own tomorrow) and whatever incentives they are offering (currently point discount plus free additional 2006 points, and no closing costs. However, you have to buy at least 150 points (160 a/o March 5th) and the price per point is a little more than resale.
Benefits of going through Resale are possible cheaper price per point, getting the resort you want, can buy less than 150 points and many owners have banked points so you end up getting "free" additional points. However, you do pay closing costs, may have to wait up to two months before becoming an owner and in the end Disney may decide to buy back your contract, so you spent the time via resale for nothing.
I highly recommend you read past posts since there are hundreds of emails on this topic.
A different site that I found very helpful was mousesavers.com. Check out the article on DVC. It helped show why you should or should not buy DVC.
Good luck!