That's an OS created volume serial number. From the OP's question, I gather he wants the hardware serial numbers.
This isn't really a C++ question, more an operating system one. That said, which Windows 64 bit - XP, Vista, Win7?
Try SiSoftware's Sandra 2009 - it's 64 bit compatible, and (at least on the older version I have) it will give the hardware serial numbers for mobo, hard drive, and lots of other information. Another good tool to keep handy is Belarc Advisor. Both products have a free, personal use version.