Answer:
You'll need a PSX Emulator. (Including Plugins and BIO(NTSC Or PAL))
A good one would be ePSXe.
ePSXe : http://www.emulator-zone.com/doc.php/psx/epsxe.html
ePSXe FAQ : http://www.epsxe.com/files/ePSXe_FAQ.txt
ePSXe Plugin Pack : http://forum.romulation.net/index.php?topic=600.0
You will need the Image File, Backed up from an original PSX Game CD or from online somewhere.
The Emulator will "Emulate" the game. Look On Forums like Emuforums.
Emuforums : http://forums.ngemu.com
P.S Spreading BIOs is Illegal, I can't link you to them.