Here are a few command line checks that a colleague of mine sent to me. I believe he put them together from several other places so I figured I would put them all in one place for easy reference. These apparently work on Windows 7, Vista and XP but I have not tested each one on each OS. So please let me know if you find one that doesn't work.
For details about the motherboard:
C:\> wmic baseboard list full
For CPU information:
C:\> wmic cpu list full
Get Motherboard - Manufacturer and Serial Number:
C:\> gwmi win32_baseboard
CPU information - Description, Manufacturer, and Speed: