The Game runs very poorly if you have very little system ram free to run the game.
Plus you have an Intel core 2 duo cpu, That has two cpu cores so to get the best out of it you should really be running a 64bit version of windows other than the 32bit version you have of windows Vista on your system.
A 32bit OS will not make use of the two cpu cores the Core 2 cpu has.
Also a Nvidia 8800 GT card or a Ati 2900XT is the bare minimum of a graphics card you need to run the game.
Most of the in game graphics settings should be set to low or medium. and any AA Anti alias should be set to about x2
or turned off.
Also the resolution you set for playing the game will have a impact on how smooth the game plays.
If you notice when scrolling across the play field it is slow and jerky, or stutters.
It because your on the bare minimum hardware requirements to run the game.
Adding more system ram, and a better graphics card.
Plus switching over to a 64 bit version of windows vista so it could use the 2 cpu cores would greatly improve how the game plays MrN1ce9uy.