To get hardware information, you need to create an object of ManagementObjectSearcher class.
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Code:
ManagementObjectSearcher searcher = new ManagementObjectSearcher(
    "select * from " + Key);
the Key on the code above, is a variable that is replaced with appropriate data. For example, to get the information of the CPU, you have to replace the Key with Win32_Processor.

for more info refer this article : http://www.codeproject.com/KB/system...formation.aspx