Awhile ago I needed to find the Serial Number of a remote machine so I could pull the drivers, traveling to see that machine became very tedious and took time. So I did some searching and came accross this command that you can run via-command line with either powershell or by remotely connecting to the machine and running this from command prompt.
If you open up a command line window you can call on the WMIC command to pull the BIOS serial number of a machine.
wmic bios get serialnumber
You can also run this WMIC command to get the computer model number.
wmic csproduct get name
For further information here is the Microsoft KB: http://support.microsoft.com/kb/558124