Tools

PStools

MoveOnBoot
Move a file at boot time before Windows can get a hold of it
PNP Util

Nessus
Nids
GPG
Encryption
Ccleaner
Cleans Windows PC- makes it faster and more secure
Windows 7 TweakUI
Over 150 Windows 7 tweaks
XP TweakUI
Windows XP OS tweaks
Process Explorer
Shows info about which handles and DLLs processes have opened or loaded
Unlocker
Unlock or force delete files that are in use
Microsoft FixIt
Fix Windows system performance problems on slow windows machines
Windows 7 USB
Create a Windows7 installer from a USB drive
XP Snipping Tool
Adds Win7 snipping tool functionality to XP
HWiNFO32
Detects everything about computer hardware (overheating too!)
Recuva
Recovers deleted files in Windows
Defraggler
Defrag entire HDD or individual files
ScanPST
Scans and repairs Outlook PST files
Copy downloaded file to here:
C:\Program Files\Common Files\System\MSMAPI\1033
Auslogics Defrag
Best defragging tool (allows for defragging PST)
PCDecrapifier
Remove apps that come pre-installed on a computer
JavaRa
Removes old/redundant Java Runtime Environments and updates to newest versions
MailPV
Recovers mail passwords from various email clients (Outlook etc...)
Windirstat
Drive space visual mapping
Uptime
Tells you how long a computer/server has been online
Nir Soft PSTpassword
Cracks password on PST files
Input Director
Software KVM

Anti Malware Tools

Microsoft Safety Scanner
Virus Scanner
http://www.microsoft.com/security/scanner/en-gb/default.aspx
Malware Bytes
Virus Scanner
http://www.malwarebytes.org/
Super Anti Spyware
Virus Scanner
http://www.superantispyware.com/
TDSS Killer
Anti Rootkit
http://support.kaspersky.com/faq/?qid=208283363
Unhide
Unhide Files/Programs
http://www.bleepingcomputer.com/download/unhide/
Combofix
Virus Scanner
http://download.bleepingcomputer.com/sUBs/ComboFix.exe
House Call - Trend Micro
Virus Scanner
http://housecall.trendmicro.com/
Spybot Search and Destroy
Virus Scanner
http://www.safer-networking.org/en/download/index.html