You will almost certainly be flying into Denver International Airport, which is roughly 70 miles (110 km) and just over an hour away from the conference hotel and conference site. On the 17th, conference attendees are encouraged to take the Fort Collins MAX, which has its main page here. There are many stations along Mason Street, which is just two blocks west of the conference hotel (west is toward the mountains), and the MAX will get you comfortably into Old Town should you choose to join the Wednesday evening event or visit Old Town on other days around the conference (or stay in one of the hotels there). The schedule is posted here.

To get to Fort Collins from the Denver airport, you can choose the Airport Super Shuttle, which I just found to be $32 each way. If you want a car to get around Fort Collins, the conference hotel has a car rental (See "Services & Amenities" tab here) service with the rental car location just a few block south of the hotel. This will be a lower rental car rate than renting from Denver International Airport (DIA), although if you plan to do any other traveling around the DocEng conference, you may wish to rent and return a car from DIA. The conference will not be providing any shuttles, so you will need to provide your own transport from the hotel to the conference (Hewlett-Packard) site and to the evening events. If you do not have a car, you can use the bus and/or carpool with other attendees. If you cannot find a ride to/from the conference, and don't want to rent a car, you may opt for a Fort Collins Taxi.