Prince Harry is planning to celebrate his 30th birthday early with a party this weekend. But at least one royal watcher says anyone expecting a loud and lavish affair will likely be disappointed.

Royal correspondent Victoria Arbiter says Prince Harry is more consumed with his latest project than his birthday this year. That project is the launch of the first Invictus Games, a Paralympic-style sporting event for injured soldiers from around the world.

The Games begin on Sept. 10 and Harry has a full schedule of appearances leading up to and throughout the events.

Harry helped launch the Games after being inspired by the Warrior Games in Colorado, a sporting competition for injured U.S. soldiers that he was able to watch last year.

"What Harry has done is he's taken it one step further and now has competitors from 14 nations competing under one roof," Arbiter said.

"The reason those Games are happening is purely because of Harry," she added.

Prince Harry, a captain with the British Army Air Corps, very much supports the aims of the event, Arbiter says. Those include giving competitors a sense of self and helping with their rehabilitation, but also using the event to show the world the sacrifices that soldiers make for their countries, she said.

"I think for Harry, he really wants to champion this and it's an opportunity for him to start making his mark, creating his legacy," she said.

With such an important event coming up next week and with all eyes expected to be on the prince, Arbiter expects that Harry's birthday celebrations will be more low-key than many might expect from a prince who's forged a reputation as a fun-loving, party boy prince.

"For Harry, he's very aware that should there be a crazy party, should there be a wild night out, that's all anybody's going to talk about. And for him, the Invictus Games are everything," she said.

Still, Arbiter says the prince's brother, Prince William and his wife Kate, are planning a weekend fete at Kensington Palace for Harry, who doesn't turn 30 until Sept. 15. There's no word on whether Kate's sister, Pippa Middleton, who published a party planning book two years ago, will be part of the organizing duties.

Diana’s gift to Harry

Prince Harry's birthday will be special for another reason as well: he and his brother will be inheriting several items from his mother Diana's estate.

Diana's wedding gown and 150 other of her possessions have been held in trust by her brother, Charles Spencer, since she died in 1997. Her will stated that upon Harry turning 30, the items would be turned over to the boys.

The items include the silk taffeta gown Diana wore to her wedding to Prince Charles in 1981, several other outfits and gowns, two tiaras, jewels, home movies and letters.