PEiD

PEiD detects most common packers, cryptors and compilers for PE files. It can currently detect more than 600 different signatures in PE files.

OllyDbg

OllyDbg is a 32-bit assembler level analysing debugger for Microsoft^® Windows^®. Emphasis on binary code analysis makes it particularly useful in cases where source is unavailable.

Freeware Windows Disk Defragmentation

http://www.mydefrag.com MyDefrag is a disk defragmenter and optimizer (a maintenance utility to make your harddisk faster) for Windows 2000, 2003, XP, Vista, 2008, and for X64. It is freeware, no time limit, fully functional, no advertisements. Fast, low overhead, with many optimization strategies, can handle floppies, USB disks, memory sticks, and anything else that looks like a disk to Windows. Included are a set of easy to use scripts for endusers, a scripting engine for demanding users, a screensaver, and a combined Windows plus commandline version that can be scheduled by the Windows task scheduler or for use from administrator scripts.