In windows server 2008 it is possible to see the top files which consume the most I/O on the filesystem using standard system tools.
How to setup the same counters, but in reverse - I would like to have a graph that shows I/O on a specific file?
The purpose of this exercise is to monitor I/O on the SQL Server - here I know which files constitute logs and database files and would like to see how much I/O is used for each of the databases running on the server (so to compare and measure I/O that is gets assigned to each database).
There is no built in tool in Windows that allows you to see which files are being written to. I'll let that sink in for a moment before moving on.
You'll want to look for another tool, and Process Monitor is a good start if not the only tool you'll need.
HOWEVER, what you probably want to do is monitor the database performance from within SQL Server itself. For example, this little beauty:
Among many other performance monitoring capabilities within SQL Server itself.