Where is Microsoft Windows SDK folder located in Windows XP and Windows 98?

I have to use Microsoft SDK directory path in my c# code. In Win 7 i can easily get it by following line(hard-coded):

string path = Path.GetFullPath("C:\\Program Files (x86)\\Microsoft SDKs\\Windows\\v7.0A\\Bin");

Is there any kind of path exist in win xp or win 98? where are netsh.exe are present in xp or 98 ?