new to the biking world, need all the advice i can get!

[delizabeth]

hello all! i'm new to the world of biking, but i've been running long distance for a few years on and off now.
any advice on what kind of good starter mountain bikes to look at? any other advice?
i don't think i'll be going into road cycling, more park paths and rough trails. i want a good, committed full body workout to get into.
thanks!