Glamour, Glitz and Juleps at Kentucky Derby

Queen Elizabeth II's betting habits are a state secret, but her love of horse racing was on display for all to see today as she made a historic appearance at the 133rd running of Kentucky Derby, won by Street Sense.

Wearing a lime green hat with fuchsia trim, the queen fit right in among the glorious hats and elegant attire. She was far and away the biggest star there, trumping decidedly b-list celebrities like rocker Gene Simmons of the band Kiss and actress Jenny McCarthy.

The aristocrats of Kentucky's blue grass thought the queen's blue blood was a perfect match. The queen's sister, Princess Margaret attended the Kentucky Derby in 1974, but this is the first time the Derby welcomed a monarch.

College student Erica Fencil was surprised and pleased to find she was sharing a private suite with royalty.

"It's unbelievable," she told Reuters. "I can't believe I'm in the same room as her."

Of the approximately 150,000 race fans in attendance, the queen might just be the most knowledgeable. She breeds race horses and apparently locks herself in on many occasions to spend the afternoon watching races on television.

At 81 years old, she still gets in the saddle every weekend she can.

Royal biographer Robert Lacy says for a queen, horses make a nice change.

"Some people say she gets on better with her horses than she does with her children," he told ABC News. "I mean, horses don't talk back, they don't know she's queen, and they have these wonderful pedigrees that she can organize. She couldn't organize her own children's weddings, but she can organize who her horses breed with."

Now that the queen's first Derby is over, she will make her way to Washington, where President and Mrs. Bush will host a state dinner in her honor on Monday.

It will be the first white-tie affair at the White House since George Bush has been president. Seven thousand onlookers will watch the queen's arrival ceremony, but only 134 lucky invitees will sit down to dinner.

ABC News' Nick Watt reported this story for "World News."