Also, if you can, rent a like-bike to the ones you are considering and take it on a trail for a day. I know that I get really nervous when I am shopping and can't really get a feel for the bike while being watched. It was TOTALLY worth it to me to rent 3 bikes on 3 consecutive weekends and take them on the same trails to find out what kind I really wanted. At $30 a day, it was an expensive investigation, but saved me from buying a bike that I wouldn't have been happy with.
Apart from that, a hardtail is a great choice, but only TITS (time in the saddle) will tell.
