When is a green card holder, a permanent resident of the US eligible for citizenship ?

Question

green card holder arrives in the US as nurse on December 25, 2004.

Answer 1

Here is the official Naturalization Handbook:
http://www.uscis.gov/graphics/services/natz/English.pdf

Answer 2

Prove your employment status,
Number of years being a resident of the US,
Proof of house or property in the US,
Good standing in the society, and
If you all have the above requirements, maybe you can already file an application with the INS for a permanent resident card.