You'll need a backwards compatible PS3, so either the original 60gb one or the 80gb NTSC-U which comes in the motorstorm bundle or Metal Gear Solid 4 bundle.
And then, to play the PS2 Iso's you'll need the Cobra USB dongle
See if you can find an old, Fat PS3 40GB model (the launch version). Those ran PSOne/PS2 games good enough for me, but the jagged lines on games like Final Fantasy X look WORSE on the PS3.