I just saw part one!
Spoiler WARNING. I'm telling everything!!
It was great! XANA's first attack was towards Jeremie, using a vending machine, they call Aelita, Mya. Jeremie found out about Lyoko because he was looking for some robot parts, and thought the factory was the ideal choice, so he went there...he was scared stiff, he turned on the supercomputer. Sissy was nearly virtualized, and so was the dog. We also find out that the reason they have those costumes, is because, that's their personality, that's what they want.