Theres a lot you can do to stop jurkyness. In importance order.
1. Defrag Hardrive (Stutters are usually due to the hardrive having to access game files, Perfectdisk is the best defragger to get)
2. Make sure that you have as little running processes as you can before you play the game, they can cause stutters when they do stuff
3. Having too little RAM can cause stutters when it has to keep filling up the RAM and is not keeping up. But that depends on the amount of RAM in your system.
4. The graphics card which you have might have too little RAM again for the same reasons as above.
5. Your hardrive is too slow. For the same reasons as 1 but because its not accessing the files fast enough.
There is more but generally those 5 points are the main reasons