This video details how to build a portable encrypted Linux operating system so you have a different computer for banking and password management than you have for general computer work and internet surfing.
This install uses LUbuntu as a full, but lightweight distro that can easily run from a small USB flashdrive. You can download the iso image and read more details here:
My personal install for this build uses a Sandisk 2.0 cruiser drive, but other USB 2.0 drives did not work in my testing, use a 3.0 drive instead. 16 GB is generally sufficient unless you will be storing more than passwords.
You will want to follow some of the setup instructions in the video A Safer Dualbook to make sure you are not overwriting your hard drive:
More videos and articles can be found at http://www.switchedtolinux.com