CCBrown,
I purchased my vehicle from Carmax. I've referred my friends to Carmax. Typically, Drive Financials is a last resort for financing. If you are approved through any other lender it is a positive. The salesmen are not paid any additional commission for the amount of car or the lender who finance through.
However, the amount down is similiar to the requirements of drive. They have certain stipulation like the car can't have more than 50,000 miles, and it can't be more than 2 years old, it can't be a certain make/model, etc. The rules are different now I am sure (I was there in Dec 2005).
I hope this helps. I wish you the best of luck.