ast May 28, Anthony Edwards, who plays ER's resident good guy Dr. Mark Greene, traded in his hospital scrubs for a fireproof suit and helmet as the official Pace Car driver for the Indianapolis 500.

"I've always been a huge fan of auto racing," said the 38-year-old actor, who had never even attended an Indy 500 before. "I think I'm really spoiling myself coming the first time and getting to drive the Pace Car."   Edwards revved up his interest in racing by completing both the beginner and the advanced courses at the Jim Russell Driving School at Sears Point Raceway in Northern California. He's also involved with the Indy Racing Northern Light Series. "I'm just so impressed how much concentration it requires for a race driver to do this for hour after hour at the speeds that they do it," he said.   Edwards was planning to simply attend this year's Indy 500 through his involvement with Cure Autism Now (CAN), a charitable, non-profit organization seeking a cure for autism. Looking for ways to raise awareness for the cause, Edwards and the organization sponsored Team CAN driver Buzz Calkins, the Bradley Motorsports entry at Indianapolis.   One thrill for Edwards was taking a practice lap before the race with 1963 Indianapolis 500 champion Parnelli Jones. With Jones' encouragement, the actor managed to goose the Olds over the 100-mph mark around the two-mile track. "Like everybody says, it's narrower than you think," was his impression of the famed oval.   After the start, Edwards watched from the pits and later checked out the action from the team suite. With two small children, son Bailey and daughter Esme, and with wife Jeanine expecting their third, he says he'll never get into racing to the same extent as fellow actors James Garner or Paul Newman. In fact, his own taste in cars is far more conventional. Edwards drove off from an interview with Playboy magazine a few years back in a Chevy Suburban.   The youngest of five children, Edwards grew up as a bit of a surfer dude in Santa Barbara, California. He drove a Honda Civic back in high school.  Before he got into racing, he satisfied his need for speed by riding the roller coasters at places like Magic Mountain and Six Flags in California.   If he ever wants to add to his car collection, money won't be a problem. The four-time Emmy-nominated actor signed a three-year, $35 million deal to remain with the NBC hospital drama through the 2001-2002 season. The nearly $400,000 per episode stipend makes him the highest paid actor in a drama series. - Bill Brioux