Also I seem to remember that Turbo C made 16 bit apps and those would not run under Windows 64. (Although with Win64 pro you are allowed download a VM and install and run winXP within this.) I think Borland C would make Windows apps so those could probably run under Win64.
If you watch ebay you can probably buy an old version of Turbo C for cheap.
Depending on what you want to do you can find free C compilers online that will run in a DOS window, and I think you can still download Microsoft Visual C++ for free.