ubuntu does not work with my graphics card

i have ubuntu installed and use livecd my graphics card is geforce2 mx400 pci but i cant get the 3d graphics to work with ubuntu i have downloaded updates for the card but still cant enable the 3d function i even went to administration/update manager/ and searched for updates still have problems i like the speed of ubuntu but i cant change my screen resoulution and i am not going out to by a new graphics card can someone please help