Tool/code/extension for tagging files

Question

There are a lot of articles on how you can tag files in Windows 7, such as: http://lifehacker.com/#!232891/tag-files-and-save-searches-in-windows-vista

Furthermore there are some tools like LunarFrog, Tabbles etc, where you can tag all the files on your system, but the tags are not saved within the files themselves.

I'm searching for a tool or some code where I have a user interface to tag the files themselves for later use with Windows Search (Windows 7).

This is my preferred way to organize my files because doing so:

• I am independent from any vendor
• I can combine search and tag functionality

Any ideas how to do this?