I have found a link:
http://www.codeguru.com/forum/showthread.php?t=249788
I think I will go for checking the BIOS SerialNumber. In the link it seems to fail when doing this on Windows 98 or earlier but if a fail meens an emty string like: "" that will work for my purpose.
They refer to get the BIOS Serial like below but when gooling on that, I am not sure if I can find anything helpful of how to return this serial number.
I use VC++ 2008 Express Edition
GetBIOSSerial(); //Is this a call, I cant find out if any namespace goes with this