Hi,
The problem here is that you're trying to run the game on an onboard GPU. Onboard GPU's rarely work with games at all, and when they do work, they give hardly any perfromance. Unfortunately, you have only two real options:
1. Get a dedicated video card. (Best option, but you've said you can't upgrade.)
2. Turn the graphics settings all the way down and play it as best you can.
The problem here is that you're trying to run the game on an onboard GPU. Onboard GPU's rarely work with games at all, and when they do work, they give hardly any perfromance. Unfortunately, you have only two real options:
1. Get a dedicated video card. (Best option, but you've said you can't upgrade.)
2. Turn the graphics settings all the way down and play it as best you can.