Hi all,
You may be interested to know about the Kalman filter, I have used kalman filters to remove the noise and drift from the gyros and merge the readings with the angle computed from the accelerometers.
There is code available for 6DOF computation in the Arduino Helicopter Autopilot thread.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1229733416
This may help - may not... depends how much headache you are prepared to put up with! It's certainly not simple, but the results are spectacularly improved.
Hope that helps,
Ed