Most .chd games won't play on modern hardware.
Area 51, Maximum Force, and the others that came out around that time work, as does Carnevil until it hits bugs.
But the remainder, Wayne Gretzky, Blitz, NBA, the fighters, Judge Dredd, Gauntlets, the Driving games, they all won't play at anywhere near good fps.
That's on a 4200+ with 2 gigabytes of ram. I'll get around 12fps on most of those. Even OC'd to 2.5ghz I can't get beyond 15fps...