Thanks for the link, Curt.
I know about that kind of softwares, but I was looking for something much simpler (no charts, no news, no "symbol lookup", etc.)
In fact, here is what I am seeking:
I enter a stock in Calc (Open Office version of Excel), and through some sort of macro, I can retrieve a stock price cross-over.
When that cross-over has been triggered, a pop-up alerts me!
That's all! (Yet, it may not be so simple to make!)