Newbie question: applications for generating XML database

[Josip]

I'm trying to determine if XML can be useful for my app.
I want to define structure for inputing data, for example:

-City-
Name: String
Area: Number
Population: Number

-Mountain-
Name: String
Height: Number

-River-
Name: String
Length: Number

Having defined the structure of data, the user should be presented with a
form to input as many objects of each type as he wants (objects are
dynamicaly created). After that the user input is handled by app.

I have seen XLS files for transforming XML data to HTML page, and I'm aware
that something similar exists for MS Word. I'm searching for a solution that
would generate input fields from my defined stucture, and store all entered
data into XML database.
I'm developing on Windows XP platform, but I'm interested in solutions for
any platform, either commercial or free.