Just signed up for my first 50K

I just signed up for my first ultra marathon called the Seashore 50k in Tidewater, VA on December 15th, 2012.  Going for a nice little 10 mile run at National Battlefield park tomorrow just to get back into the swing of things.  Took a week off after the marathon with no running, did a few 5k easy runs this week but would like to get back and need to adjust to the trails more.  My goal for this race - finish as it should be with any race but I was hoping to do something around 6 hours or less.  God, I hope I am not running for 6 hours but who knows.  Last year, the weather there was pretty bad so I really have no idea.    Next week, I have a 20 and a 10 on the weekend so lets hope the legs hold together.  The achilles has been ok but I have to stay on top of it and make sure I don't let that tendonitis come back like it did in March....on to training...