Freeware Windows Hardware Information and Diagnosis Software: HWiNFO3

HWiNFO3 is a freeware Windows tool which can provide comprehensive system and hardware information and diagnosis. Among the info HWiNFO3 can provide:

Comprehensive hardware information (Motherboard, Sensors, BIOS, CPU, chipset, PCI/AGP, USB and ISA/PnP Devices, Memory, Video Card, Monitor, Disk Drives, CD/DVD Devices, SCSI Devices, S.M.A.R.T., Ports, Printers and so on)
System health monitoring (Thermal, Voltage, Fan, Power)
Basic benchmarks

You can save these reports in CSV, XML, HTML or MHTML formats.

Screenshots:

HWiNFO32 @ Dual Intel Xeon 5150 Server	HWiNFO32 @ Intel Core2 Duo T7300 Notebook
HWiNFO32 @ Intel Itanium2	HWiNFO32 Benchmarks

HWiNFO3 works on Windows 9x/2000/XP/Server 2003/Vista/Server 2008/Windows 7, both 32-bit (IA-32) and 64-bit (x64, IA-64).

Download HWiNFO3 | Thanks to tinhed for the tip!