Maintenance

CCleaner - Clears out junk that may slow you down
CPU-Z - Identifies components
HWMonitor - Displays sensor information

Malware and Virus Protection

Microsoft Security Essentials
Emsisoft Emergency Kit (at page bottom)

Open Source Software

Ubuntu - Operating System
GIMP - Image Editing

Tutorials

_Inpics - Tutorials for Open Office, MS Office and Web Development with lots of pictures

GCF Learning - Tutorials for MacOSX, Facebook, Google Docs and more.

Microsoft Training - Videos and lessons for using Microsoft Office products

W3Schools - Tutorials for web development