I disagree. H20 Laurie was a terrified Laurie traumatized by nightmares and visions of Michael, coping with pills and booze. She was running scared from her past. That's very real. I love both performances. She does a great job showing the emotional scars of Laurie from two different possible outcomes that someone could have from an experience like that. Both are valid, and she did both equally well.
She had some brilliant scenes in H20. Even Josh Hartnett with limited acting experience back then did a good job, and I liked her relationship with him. Different to Karen. Instead of teaching John to fight and shoot a gun, she wrapped him in cotton wool and was so overbearingly protective. H20 was a great Laurie story and was the only time in the franchise where they did something interesting with the Michael wanting to kill his family storyline.