dxdiag
The dxdiag utility included with DirectX allows you to not only display all system information but save it in an easy to read text file. To run this utility click Start, run, and type: dxdiag and press enter.
msinfo32
Run the Windows System Information (msinfo32) that comes pre-installed with Windows to determine installed hardware and software specifications.
Device Manager
Generic hardware information of what Microsoft Windows is detecting can be found through the Device Manager.
WinAudit
http://pxserver.com/WinAudit.htm
Fantastic free and small program and our highest recommended program for detecting and listing the hardware and software in a computer. Below is a listing of what this program is cable of detecting.
* Operating System and system model type
* Computer model and serial number
* Processor speed and primary and secondary cache amount.
* Type of BIOS, display, peripherals, and other system information.
* Installed programs.
* Security information such as open ports, shares, Internet utility versions, network groups and users, etc.
* Scheduled tasks, error logs, and complete uptime statistics.
* Installed memory including what size of chips and what bank their installed into.
* Drives including hard disk drive manufacturer, size, SMART status, network drives, and other disc/diskette drives.
HWiNFO / HWiNFO32
http://www.hwinfo.com/
Another great software tool for getting a comprehensive list of your hardware information that is available as a 14 day trial. In addition to detecting as much and in some cases more than all the programs listed on this page the program is also capable of displaying sensor information used for detecting the temperature of the motherboard, CPU, and any other devices and displaying voltage and fan RPM speeds. Finally, the program also includes a benchmarking comparison that can be used to compare your computer against other hardware.