You will need to get a graphics card, nvidia 8400gs 512mb or above will do depending upon your budget. Then you will be "able" to play on the low settings. If you really want to enjoy the gameplay then you will need to get a whole new pc.
My very first pc was a Pentium Dual Core, 2 gigs of ram 120gb hdd, nvidia 8400gs 512mb and windows xp. Almost similar as urs, was able to play iv on low settings.