What is Dropbox?
Well, you have ever lost your files on reformat/windows reinstall ?
That's a bad feeling, when you work for a project for 3 months, and your HDD just dies.
With dropbox you have like a FTP folder, directly on your PC.
You just copy/paste/delete/edit files on your folder, and they automaticaly gets modified and hosted on your Dropbox account.
For example, you have some music that you want to keep, you copy it on your dropbox folder, and after you can smash your PC or whatever.
Then, if you log on another PC, even phone, you can have the same folder (with your saved music) .
Always have your stuff when you need it with @Dropbox. 2GB account is free!