The first brew I ever did was a double batch of the NB 'Fat Tire' clone. It tasted absolutely nothing like a Fatty, but it was decent all things considered.
Even with all grain I've had difficulties trying to clone it exactly, although I am close. The best advice I can give is to use american ale yeast and not the belgian strain they offer (although I had some good results with Wy1098 fermented low). Since you're doing extract, I'd also go heavy on the steeping grains. My all grain recipe is about 70% pale malt, 17.5% munich, 10% victory, 2.5% crystal 80. If you can partial mash the specialty grains with a lb or two of pale malt, then you'll be able to get the rest of the fermentables from standard DME or LME.
