If you want a secure delete function for any sensitive files, Xplorer2 (by Nicos Bozinis) from www.zabkat.com
has a feature called "shred" files. This is an excellent explorer replacement (from $29.95) for all windows versions including windows 7 and supports both x86 and x64. The author claims that once a file is deleted with "shred" command, it is impossible to recover this file again. The "shred" function is as easy to use as a normal delete file function.
By the way, the freeware CCleaner has a feature to wipe the free space (including MFT area) securely (1, time, 3 times, 7 times and 35 times etc.) for securely cleaning the free space for those who are security conscious. This can be run whenever the system is free as it takes a long time... This can even securely clean a hard disk completely if necesssary.