Sometimes, the PLUGINS and configurations are more important than your PC specs.
Click on config--> configure.
U have to set the plugins required for your game.If u don't see any plugins, U can click on "set plugins directory" and selecting the directory where your plugins are installed. If u don't have any plugins on your computer, u may download them from net(they are free) just google it.
Now, the main thing that comes is BIOS. legally speaking, it is illegal to have bios if u don't own a PS2. but try googling it and U will get them easily,
then select your configurations, click on config--> cdvd rom and set the directory where your games' iso file is located.
Click on file-> run CD/DVD and HOPE FULLY your game should RUN.
if not, u can try other settings and keep on experimenting until u succeed.....
GOOD LUCK!