Halo running choppy on Pentium D?

That pentium d is a single core processor meaning two cores on a single die, the card i have on my old pc nvivdia geforce fx 5500 256mb is not good for gaming especially halo,with a dual core processor and that geforce card you probably will get to medium settings without a problem, and if you are using ddr ram really not good for gaming as well,upgrade your pc.