I think Lindsay has a certain amount of street smarts and probably toughened up a bit in jail, but Sarah is certainly in better shape and has legitimate training in martial arts.  Lindsay does have some size advantage, of course.  I think the bottom line is that IF Lindsay is sober and together she'd have a reasonable chance of winning, particularly if it was a street fight scenario.  However, if she's out-of-shape and strung out, Sarah would almost certainly take her apart.  In short, the circumstances of the battle would pretty much determine the outcome.
-JM