Princes Harry and William
06/15/2007 at 09:00 AM EDT
The Princess Diana that her sons remember was the bubbly, joyful mom they would find dancing around the room to Supertramp, Michael Jackson and Elton John.
tells the BBC in an interview to air June 29 that music and dancing were a "big release" for Diana: "We used to catch her dancing to her music – we'd walk out of the room rather embarrassed that our mother was just dancing around."
William, who turns 25 on Thursday, says he and his brother Harry want the upcoming Concert for Diana
to celebrate their late mother's "whole spirit – her joy of life and everything that we thought she stood for."
"After 10 years there's been a rumbling of people bringing up the bad and over time people seem to forget – or have forgotten – all the amazing things she did and what an amazing person she was," William tells interviewer Fearne Cotton. "She's not here to defend herself when she gets criticized."
(To see a clip of the interview, click here
The concert will be held on July 1, which would have been Diana's 46th birthday. The princes said the event was a fitting celebration during the summer that marks the tenth anniversary of her death in Paris.
Artists performing at the Wembley Stadium event include Elton John and Supertramp along with Diddy, Joss Stone, Lily Allen and Duran Duran. David Beckham is to be a presenter, PEOPLE has learned, after he was asked personally by the princes to introduce one of the acts.
Diana, says Harry, "was a happy, fun, bubbly person who cared for so many people." William says he and Harry were "so lucky" to have Diana as their mother, adding, "there's not a day that goes past when we don't think about her and miss her influence."
In other Prince William and Harry news, NBC on Friday released more excerpts from their interview with Matt Lauer
. They reveal that Diana used to call William "Wombat" – and the nickname has stuck.
"I can't get rid of it now," William says of the moniker coined "when I went with our parents [to Australia] and the wombat ... obviously, that's the local animal. So I just basically got called that. Not because I look like a wombat. Or maybe I do, you know, [a] little."
When Lauer asks, "What's the coolest thing about being a prince?" William says: "We're very lucky. We have, you know, all these sort of nice things around us. And so we're grateful for that because so many people don't have that. We have relative stability and stuff like that. Lots of things that everyone would love to have."
"Yeah," adds Harry. "We've had a good education. Doesn't show, but we have."