I have solved problem 6 of Project Euler. I created a google code hosted project here where you can check out the solutions to the problems I have solved. In particular the solution to problem 6 is here
The solution only has the optimization of finding the sum of the nth number through the formula
sum(n) = n * ( n + 1) / 2
Hope the solution is understandable. If not, don’t hesitate to put a comment.