You can use the NetRemoteTOD function.
An example from http://bytes.com/groups/net-c/246234-netremotetod-usage:
// The pointer.
IntPtr pintBuffer = IntPtr.Zero;
// Get the time of day.
int pintError = NetRemoteTOD(@"\\sony_laptop", ref pintBuffer);
// Get the structure.
TIME_OF_DAY_INFO pobjInfo = (TIME_OF_DAY_INFO)
Marshal.PtrToStructure(pintBuffer, typeof(TIME_OF_DAY_INFO));
// Free the buffer.
NetApiBufferFree(pintBuffer);