I want to purchase a PNY Technologies GeForce 6200 256MB AGP?

but when i look at the specifications, i saw under system requirements i saw Pentium III - RAM 128 MB - HD 50 MB i am not sure if my computer has the Pentium III and HD 50 MB. do i need to have these in order for it to work. and please state where i can find other graphics cards on the internet.