System Information, Testing

Benchmarks
3dMark (shareware)
http://www.futuremark.com/

Prime (free)
http://www.mersenne.org/

Super-PI (free)
http://superpi.ilbello.com/

System Stability Tester (os)
http://systester.sourceforge.net/

Information
Everest (free, discontinued)
http://www.google.com/search?q=everest&ie=utf-8&oe=utf-8&aq=t

SiSoft Sandra (free)
http://www.sisoftware.net/

CPU-Z (free)
http://www.cpuid.com/

Motherboard Monitor (free, discontinued)
http://www.ocinside.de

Speedfan (free)
http://www.almico.com/speedfan.php

Testing
Memtests
http://hcidesign.com/memtest/ (free)
http://www.memtest.org/ (os)

HDD-Tests
http://www.hdtune.com/ (free)
http://www.datec.de/down_hd.html (free)