I always install at least 3 drives each dedicated to the OS, media, & rendering.

I second what Michael said..
You really need 3 drives to "bounce" your renders around.
eg. System drive A is not used in any of this except delivery, I capture to Drive B , then make proxies to C drive. Use the proxies to edit, then replace the files with the originals on drive B.
Render cut project via Lagorith to drive C.
Add Titles and any updates to audio, final touches, then render delivery format to Desktop (system drive). Probably should use another drive for final render, but its handy on the desktop, and Lags to H264 is always an easy render.
Bottom line is never render to the same drive as source files.