I'll echo this.  Microsoft's UX guidelines notwithstanding, I never install anything that allows any option to do otherwise on the C drive of my main workstation.  General apps (and app content like fonts, stock art, asset libraries, etc) go on the D drive.  Games go on the E drive. (I have 14 spindles in that machine, six on mainboard SATA ports and 8 more on a raid controller.  Several general partitions, a striped multi-disk Windows volume for video editing and other high-bandwidth apps, and