Hi Mamaspank! If you go to runnersworld.com and look under training, there are links to a variety of half-marathon training schedules. Typically, a training week consists of 3 or 4 running days, one of which is a "long run". Most beginner training schedules have you increasing your long run by one mile per week increments, until you reach 10 or 12 miles. Since you already have a 5 mile base, a half marathon should be very doable, given sufficient preparation training time.
Other links that you may want to check out are Hal Higdon's training web site which has great beginner info (
www.halhigdon.com) and Jeff Galloway's web site - he is an advocate of using run/walk intervals for training and racing (
www.jeffgalloway.com). Also John "the penguin" Bingham, has great stuff on his web site (
www.johnbingham.com).
I love half marathons, it's my favorite race distance. I did a full marathon once, but that was just too much for me. It got to be way too much like work, my knees started bothering me, etc. But a half marathon is enough to be a challenge to train for, but not so long that the training takes over your life. I call it .. all of the fun, with less than half the work! You still get to participate in a big event, get all of the crowd support and entertainment fun, AND a shiny medal at the end.
If you are comfortably running 5 miles, 4 times per week, you can absolutely train for a half marathon. And once you do one, you may find that you're hooked!!!