WtvWatch

WtvWatch- If you are using Windows Media Center to record television shows, you have probably already developed the habit of deleting every episode that you watched immediately. Although this is probably the best book keeping strategy possible, sometimes you might accidentally delete the beginning of another show that was located at the end of the recording you just deleted. To avoid this, you might consider leaving your recordings on the disk until you are sure that you have seen everything. However, with new recordings coming in every week, this can get confusing all too fast. The primary reason for this is that Windows Media Center does not provide a built-in indication for what recordings you have already watched. With the WtvWatch plugin, you can retrofit Windows Media Center with this feature.

http://marcus.handte.org/2011/09/13/keeping-track-of-what-you-have-seen-with-wtvwatch/