The fix for the 737 rudder was to change from two actuators to three, adding additional redundancy in case one of the actuators misbehaved (according to the Discovery documentary). Supposedly the fix has been rolled out throughout the U.S. fleets.
The SilkAir crash was a pilot suicide, not a rudder problem.
The Billings "problem", though it might have been a rudder vibration problem, it's description doesn't sound anything like the "unintended actuation" problem. Planes occasionally have vibration problems, an F28 had one in PDX last year.
The exploding fuel tank may have been a terrorist bomb (the Prime Minister was scheduled on the flight).
So when you come down to it, the "unintended rudder" problem has only been shown to have caused 2 crashes out of 80 Million flights. If you are worried about that, go play the lottery now, cause you are hot, hot, hot!!! In reality,the 300/400/500 models have a fatal accident once every 3 Million flights. Fly a 737 once a day, and you are guaranteed to be involved in one in oh, about 1,000 years.
Note; This record includes the Piedmont flight that lost cabin pressure, and one passenger died due to "natural causes", the Thai explosion that occured before any passengers boarded, and numerous crashes with survivors, making the 1 in 3 Million flights over-state the risk, the typical passenger probably has about close to 50% chance on average of surviving the wide definition of a "fatal accident".