Choose the best, not the first!
Do you have sensitive data? Than you're probably looking for encryption software. The hard thing is to choose, which one suits you the best. I have taken the time to review various packages. So you can choose from one of these.
1. Folder Lock
Folder Lock came out as a definite number #1. It's standing out in: usability, features and security. Folder Lock is able to encrypt any file / folder of any type. This means you can also encrypt USB devices or any portable media. It's acknowledged by many software websites and has won various awards from CNet, Brothersoft, PCWorld.
It has been tested by experts and proven to be the fastest encryption software. You won't even notice it is running. I highly suggest you try it for free here: Folder Lock Free Trial.
TrueCrypt was pretty close to Folder Lock in rankings, although it lacked in usability. Truecrypt is better suited for people, who are more "techie/geek". The biggest advantage is that TrueCrypt is free. It's licensed under open source, which means you can use it for free forever. However I still think Folder Lock is worth the money. If you are low on money, I suggest this one, but you could also try the free trial of Folder Lock.
You can download TrueCrypt from here: TrueCrypt