how do I detect user operating system

I have the following code to obtain user details:

HttpBrowserCapabilities bc = HttpContext.Current.Request.Browser;
string UserAgent = HttpContext.Current.Request.UserAgent;

ENT_TrackingData ret = new ENT_TrackingData()
{
    IPAddress = HttpContext.Current.Request.UserHostAddress,
    Browser = bc.Browser + " " + bc.Version,                
    DateStamp = DateTime.Now,
    PageViewed = HttpContext.Current.Request.Url.AbsolutePath,
    NodeId = UmbracoHelper.GetCurrentNodeID(),
    IsMobileDevice = IsMobileDevice(UserAgent),
    Platform = bc.Platform
};

This works great but I noticed that the Platform always says windows NT for my machine not Windows 7. Is there any way to detect this type of information in ASP.Net?