Steve,
If a domain is regged at Godaddy and it expires, it WILL go to TDNAM. Dont waste your money buying a backorder at Godaddy (I sense they will be doing away with their paid BO's eventually anyhow). If the domain is good though, you may want to consider contacting the current owner to see if they want to sell. Often times you'll get a bargain price compared to what it might go for if it hit the Drop Auction.
Justin