call of duty4 install probelm?

[xrtng]

ok so i downloaded call of dutyMW1 on gamestop i ran the installer the problem is it wont let me download the game in the folder or set up so whenever i pick a folder and click next it will say something like there is not enough disk space but i have 300GBfree(computer) to use O_O and it also said that plz free up ur disk space (WTF) or modify ur selctions (i dont get what it means O_O sry i am only 13) so can anyone help me???? on this problem??

[xrtng]

btw i bought codMW2 at gamestop the harddisck not download and i can run that game fine(setup,campagin[sad that ghost diedT_T],online, its all okay) but MW1 just wont work btw i got MW2 b4 MW1 just to let u know