Scan port by timer

Hello there,

I'm new to driver development and I'm a little bit confused with DDK &
Visual C++ and other stuff

Is where any source code for both driver that scans some port by timer and
when report port changes to an application and the application that reads
data from driver by some event?

I need to build driver for custom made computer with digital I/O, and I need
to scan this I/O with 25ms intervals.
I'm planning to use WinXP embedded for this purposes.

Any help appreshiated.

Thank you.