First of all yes you need your CD4 in order to run the game or the no cd crack which you can download it from here:
As about your systems specs i think that your problem has to do firstly with your VGA card and secondly with you RAM.
I dont think that MX 400 will be the best solution to get the better performance of your graphics but if you are not very assuming you will see your game running...As about memory i believe that you have to upgrade it at least to 1gb.
My opinion is that,if you have the budget, try to search a better VGA card.
Im sure that you will get more answers to your problem by people which are more experts from me in this issue.
And BTW....Welcome to Flyaway