Not to put too fine a point on it, but check note #1 in the requirements for the game.
http://www.hitechcreations.com/ahgs/minimums.htmlPerformance is going to drop some due to the fix that corrected trees from being dropped from rendering. There is no way around that.
I would like to know what was suggested to you that caused the lockup of Vista. Unless it is a bug in the operating system related to laptops, which it could be, there is nothing that we would suggest that would have any effect such as that.
The only risky suggestion would be the sticky in this forum about improving performance for Vista. That list has been beat to death by desktop users with minor issues. It is also noted to be risky.
Keep in mind that the same hardware running Vista is going to be about 25 to 30% slower than the same thing running Windows XP. It is possible to get a faster computer and have it run slower than before. I cannot count how many times I hear the phrase, "My previous XP box was faster! What's wrong with your game?!?!". Not sure why people do not understand Vista is a huge resource hog. It is general knowledge.
The video card in your laptop is a very low end chip and is going to suffer performance issues. Remeber, laptops are all about saving power. You can buy laptops with high performance video chips in them, but at the cost of very short battery life and very high costs.