stuttering&pausing

hi guys my sys is 2.8 p4,m/board p4p800-se,512ddr400kingston dual ram 256mb radeon 9600xt graphic card,2xhdr 80gb x7200,20gbx7200 western digital,my problem is i cant get it to run smooth now don't get me wrong the frame rates are pretty good with most sliders up 28-30 steady.it is just stutering all the time .when you bank left and right it starts to pause,for a split second.would a faster hard drive do the trick and which one for i don't have much knowledge on this area.i have updated all drivers as well only have fs2004 on main OS.also went back to 4.2 cat drivers cheers mark(ybmc)