Not good enough to rid you of index.dat.
There are detailed instructions in this thread:
http://forum.fuckmicrosoft.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=10&t=000001Many of those programs will not allow you to delete index.dat files because *.dat files are usually files associated with something crucial to the operating system (strong emphasis on "usually.")
If you really want my advice, restart in MS-DOS mode, and type "format C:" (without the quotes) when you see the blinking cursor. Then, it will ask you the "magic" question. If you type "y" (without the quotes) for YES, your problems will all go away. Just make sure you have a Linux CD handy.