Games don't run after i installed hd2600xt ! !

i had a x1550/1300 and they ran low but i could play now i try to run them and they crash ,i even reinstalled the os (xp sp2) the whole 3 pointer ! etc etc but they still crash and when one runs i install the next game and that 1 messes up the other ones , i got sumthing like " error need at least 5mb or free space on installed hdd disk" from cod world at war . fear i get "invaled video rendering sumthing sumthing" far cry 2 crashes in the intro drive sceen etc etc why ? my old lol card ran them barely at low but still ...i barely got the card tuesday was going for the 4670 but the cash not enought even do its cheap ...any ideas?

i have the new 8.12 i think thats what there called not savy on drivers lol, oh sorry ! i have around 20gb on both hdd the games r installed on diff. hdd either way i have over 20gb on both free ,the fear error only comes out after i install another game which one idk since the times i tried they were different ,i donwloaded new directx 9c drivers etc etc ,i can't tell u what the error said since i uninstalled it already sorry ,but it did run after i installed it ,i did the benchmark it has built in(fear) so its making me angry ,sorry my hands are cold 2many mistakes and 2 top it up typing big weakness