expsxe audio scrambling and than freezing

need helpe please as im very frustrated sort of.Myc omps 2.4 quad core with 3 gig ram and geforce 7100 card 256 mb i think could be less but plays ut 2004 fine with constant frame rate.I'v tried messing with different video plugins and it seems it keeps slowing down whatever i choose.Including the petes open gl drive at just basic resoultion with no special effects and still slow down? what am i missing please help what do i need to do

also bought this comp this year so why can people play it better than me 8 years ago?