Hi there Jaefo
the answer to your question could be as complex or as simple as your project is i guess. To clarify, are you after a simple sum of the individual task durations? Or are you after techniques for visualising the project timeframe?
Chandoo has a Project Management course coming up (or may have already started) which may be ideal for you if you are managing a lot of projects.
At a simple starting level I would firstly list all of the tasks, and their expected duration. You could use several columns to show various scenarios, i.e. shortest likely time, midpoint, longest likely, etc. Summing each of these columns up would provide a likely range for the total project duration.
In terms of managing the whole project, which would probably be the next step,
you would need to sort them by order of occurance, and identify any linked and dependent tasks. Once you have that initial information pretty solid and in order, then im sure someone will be able to help you out with the more technical aspects of visualising the project timeline.
Hope that helps
