What's the Name of That Book??? discussion

Okay, I read this book around 2005/2006.
It's a children's book, maybe middle school as well.
To the best of my memory, there are three children from three different worlds:
One is a boy from Earth who lives in a city and hustles people on the street for a living (card games and such). He starts getting too good at the cards--- like magically good.
The second is a girl from a warrior/Valhalla type planet. Don't remember much about her.
The third is a boy from a super high-tech type planet where no one ever leaves their homes, spending most of their time in a virtual reality. One day he decides to leave his house for the first time ever. Unfortunately, he can't find his home again because they all look the same.
Through some way or another, they all end up on the same planet together, find out they have magic abilities, and go under the training of a wizard who turns out to be evil and in the end of the book they defeat him. There is a lot of significance in "true names" and all three of the kids go by nicknames. It was the first in a series, and if I recall correctly, there was some sort of super evil they had to defeat in one of the later books.
Genre: Fantasy, Children's books
It was a physical book, and the cover had the three kids on it.

Let me know if any of this rings a bell- I'm trying to find it so my little brother can read it.

This sounds similar to Book of Names

Book of Names by John Peel is the first book in the "Diadem Worlds of Magic"

Here is the cover with 3 kids

Here's the description of the 1st book:
Three teenagers from very different worlds--Score, a streetwise New Yorker; Renald, who prepares for a medieval battle; and Pixel, who is confined to the one-room world of Virtual Reality--are kidnapped and plunged into a perilous odyssey as they seek to unlock the secrets of the Diadem.

It seems to be a quite popular book. Several readers have popped up on here searching for this book.

That's it! Thanks!!!

You're welcome :)

This is a popular book. This is the fifth time it's been "found" by this group.