The SerialPort class introduced in .NET 2.0 is definitely better than writing unmanaged Win32 API calls to access the serial port, but this is much better.

Without going into too much detail, a recent project of mine required that my application interface with an obscure device via RS232 and the serial port.

To do what I needed the device to do required me to manipulate the signal (high/low) on the RTS pin; the .NET framework's SerialPort class didn't really give me a mechanism for doing so.  Wanting to leave writing Win32 API p/invoke calls a last resort, the first result in a Google search for "better .NET serial port" led me to this article on CodeProject which described CommStudio's CommStudio Express which includes a much better serial port (SerialConnection) class which quickly enabled me to get past my little setback an on with the application. Best of all it's free!

I hope this referral link helps you.