All of the following tools are free of charge:
Antivirus – AVG Free
Free to use and very reliable. Be aware that if you install the Email Scanner component, a short message will be appended to all email you send out. You can this disable it in Email Scanner properties.
Eraser (free) will delete individual files, entire partitions and clean the empty space on your drive for traces of deleted files. Darik’s Boot and Nuke (free) does what it says. It boots from a cd or floppy and destroys all data on a hard drive.
SpinRite (US$89) is your best bet for recovering failed hard disks. It attempts to scan and repair faulty sectors. R-Studio (US$79) is a toolkit of recovery tools for damaged hard disks and deleted files. Restoration (free) will search and recover deleted files.
Disk Encryption – TrueCrypt
Creates encrypted container files which can be mounted as drives or encrypts entire disks.
Firewall – Comodo Firewall Pro
There is a stand alone free version. In my experience and from everything I have read, it is the best consumer firewall on the market.
Password Manager – KeePass
Port Activity Monitor – CurrPorts
Software Vulnerability Auditor – Secunia PSI