As a long time dog owner... 6 dogs plus several more as a foster owner... I'd suggest you focus on a dog that's a great companion rather than a running partner. I'd also recommend that you go to PetFinder.com, enter NH for location, and see what dogs are available nearby. Getting a dog from a rescue organization means that the dog is house trained and the foster owner can tell you something about the dog's personality, energy level, and ability to run on leash. I found several rescue organizations in your area: Mary's Dogs, One Tail at a Time Rescue, Alpha Dog Rescue, and a few more.
Also, some breeds that are great runners can be hard to train: Border Collies and Siberian Huskies have been mentioned, so let's look at them. Huskies can be stubborn as a post and constantly test your leadership boundaries. Border Collies (I have one) can be almost neurotic in their need to exercise. Given a choice between the two, I'd go with the 30 lb border collie over the 70 lb huskie... but then every dog has its own personality.
If you go with a rescue dog that's a year or two old, you'll have a much better idea of whether the dog is going to be a good running companion or not. That said, even good running dogs can have a short running career. My border collie, now age 10, can't hang with me at more than a 10 minute pace for a couple miles. When he was younger, he could easily handle 10 miles if it wasn't hot.