In .NET/C# test if process has administrative privileges

This will check if user is in the local Administrators group (assuming you're not checking for domain admin permissions)

using System.Security.Principal;

public bool IsUserAdministrator()
{
    //bool value to hold our return value
    bool isAdmin;
    WindowsIdentity user = null;
    try
    {
        //get the currently logged in user
        user = WindowsIdentity.GetCurrent();
        WindowsPrincipal principal = new WindowsPrincipal(user);
        isAdmin = principal.IsInRole(WindowsBuiltInRole.Administrator);
    }
    catch (UnauthorizedAccessException ex)
    {
        isAdmin = false;
    }
    catch (Exception ex)
    {
        isAdmin = false;
    }
    finally
    {
        if (user != null)
            user.Dispose();
    }
    return isAdmin;
}