'Ultra Defragmenter', and 'Trust-No-Exe'

Ultra Defragmenter

UltraDefrag is a powerful Open Source defragmentation tool for Windows NT. It is very fast, primarily because the defragmenting is done by a kernel-mode driver utilizing three interfaces: graphical, console and native.

http://ultradefrag.sourceforge.net/

Trust-No-Exe

An executable filter for Windows that prevents users opening suspicious executables.  However, Trust-No-Exe has the ability to weed out the more threatening files, meaning it won't be a total pain in the neck.

http://www.beyondlogic.org/solutions/trust-no-exe/