you can't hook up your ps2 to your computer directly as such ...

BUT: you can download a play station emulator called ePSXe which will make your computer run playstation games with a bit of fiddling ... its rather a pain to get working, but it will allow your play station games to run on your computer ...

then your best bet would be to copy a ff7 pc safe file from someone (i can give you one if you want) and use another program to make it run under ePSXe ...

its rather complex, much much easier if you can get a copy of FF7 for PC ...