Instructions
Check the USB ports on your PS3. If the system has four USB ports, your system should be designed to play PS2 games.
Go to the website at us.playstation.com/support/compatiblestatus/index.htm. Select the "80 GB Playstation 3" option, and type in the name of the PS2 game you wish to play in the text box.
Click the "Search" button to begin a search for your game. Only a select few PS2 games are not available for play with the PS3, so finding the game on this website should not be a problem.