I really don't think Spidey 2 will be number 1 again.
"I, Robot" will do decent and it is going against "The Bourne Supremacy" and "Catwoman."
Also, Spidey 2 isn't doing as well as "Shrek 2" is.
As of the 19th day, this is how much each film made:
Spidey 2: $302,287,882
Shrek 2: $314,523,202
EDIT: Preidctions for next week:
1. The Bourne Supremacy
2. Catwoman
3. I, Robot
4. Spiderman 2
5. Anchorman
6. F 9/11
7. Cinderella Story
8. King Arthur
9. Notebook
10. Dodgeball